| 1 | Wpp PLC | Unitedkingdom | Saint Helier | 13 Castle Street | Saint Helier | JE1 1ES | N/A | 2012 | $18,686,900,362 | 111,281 | N/A | N/A | N/A |
| 2 | Dentsu Group INC. | Unitedkingdom | City of London | Simlaw Services Ltd. | London | EC2Y 9SS | N/A | 2001 | $9,263,000,000 | 20 | N/A | N/A | N/A |
| 3 | Facebook UK LTD | Unitedkingdom | Saint Johns Wood | 10,brock Street | London | NW1 3FG | N/A | 2007 | $3,497,009,254 | 6,338 | N/A | N/A | N/A |
| 4 | Dazn Group LIMITED | Unitedkingdom | Shepherd'S Bush | 12 Hammersmith Grove | London | W6 7AP | dazngroup.***** | 2007 | $2,863,300,000 | 2,587 | N/A | N/A | N/A |
| 5 | Job And Talent Holding LIMITED | Unitedkingdom | Moorgate | 12 New Fetter Lane | London | EC4A 1JP | N/A | 2016 | $2,006,661,762 | 99,265 | N/A | N/A | N/A |
| 6 | Mms UK Holdings LIMITED | Unitedkingdom | Shepherd'S Bush | 1st Floor 2 Television Centre | London | W12 7FR | N/A | 2003 | $1,707,615,950 | 9,281 | N/A | N/A | N/A |
| 7 | Img Media LIMITED | Unitedkingdom | Chiswick | Building 6 Chiswick Park | London | W4 5HR | sntv.***** | 1960 | $689,140,727 | 1,017 | N/A | N/A | N/A |
| 8 | The7stars Group Holdings LIMITED | Unitedkingdom | Marylebone | 6 - 9 Floor | London | WC2B 4PJ | N/A | 2021 | $572,756,837 | 331 | N/A | N/A | N/A |
| 9 | Talon Outdoor LIMITED | Unitedkingdom | Marylebone | 130 Shaftesbury Avenue | London | W1D 5EU | talonoutdoor.***** | 2007 | $543,001,443 | 333 | N/A | N/A | N/A |
| 10 | Jcdecaux UK LIMITED | Unitedkingdom | Brentford | 991 Great West Road | London | TW8 9DN | jcdecaux.***** | 1982 | $505,556,529 | 507 | N/A | N/A | N/A |
| 11 | Rightmove Group LIMITED | Unitedkingdom | Tilbrook | 2 Caldecotte Lake Business Park | Milton Keynes | MK7 8LE | rightmove.***** | 2000 | $486,948,348 | 754 | N/A | N/A | N/A |
| 12 | Inside Ideas Group LTD | Unitedkingdom | Saint Johns Wood | 151 Rosebery Avenue | London | EC1R 4AB | oliver.***** | 1917 | $469,325,033 | 4,351 | N/A | N/A | N/A |
| 13 | Adm (group) LIMITED | Unitedkingdom | Saint Giles | Bedford Row | London | WC1R 4HE | mjgroup.***** | 1992 | $428,151,355 | 764 | N/A | N/A | N/A |
| 14 | Taboola Europe LIMITED | Unitedkingdom | Moorgate | 2nd Floor Aldgate House | London | EC3N 1DL | N/A | 2012 | $422,756,212 | 200 | N/A | N/A | N/A |
| 15 | Dentsu UK LIMITED | Unitedkingdom | Saint Johns Wood | 10 Triton Street | London | NW1 3BF | dentsuaegisnetwork.***** | 1972 | $410,519,599 | 2,863 | N/A | N/A | N/A |
| 16 | Wpp Media UK LIMITED | Unitedkingdom | Herne Hill | Sea Containers House | London | SE1 9GL | wpp.***** | 2003 | $395,486,347 | 1,123 | N/A | N/A | N/A |
| 17 | Wpp 2323 LIMITED | Unitedkingdom | Herne Hill | Sea Containers House | London | SE1 9GL | wpp.***** | 2001 | $363,021,119 | 16 | N/A | N/A | N/A |
| 18 | Ogilvy & Mather Group (holdings) LIMITED | Unitedkingdom | Herne Hill | Sea Containers | London | SE1 9RQ | ogilvy.***** | 1895 | $321,804,588 | 593 | N/A | N/A | N/A |
| 19 | Hemingways Marketing Services LIMITED | Unitedkingdom | Ripon | Metcalfe House | North Yorkshire | HG4 1PB | hemingways.***** | 1947 | $321,387,387 | 151 | N/A | N/A | N/A |
| 20 | Omnicom Media Group UK LIMITED | Unitedkingdom | Rotherhithe | 90-100 | London | SE1 0SW | ti-media.***** | 2002 | $313,956,289 | 1,655 | N/A | N/A | N/A |
| 21 | T&P Media LIMITED | Unitedkingdom | Marylebone | 15 Rathbone Street | London | W1T 1NB | msixagency.***** | 2008 | $303,620,348 | 237 | N/A | N/A | N/A |
| 22 | Global Outdoor Media LIMITED | Unitedkingdom | Marylebone | 30 Leicester Square | London | WC2H 7LA | heart.***** | 1994 | $269,300,278 | 388 | N/A | N/A | N/A |
| 23 | Bauer Media Outdoor UK LIMITED | Unitedkingdom | Marylebone | 33 Golden Square | London | W1F 9JT | clearchanneldirect.***** | 1969 | $249,822,967 | 645 | N/A | N/A | N/A |
| 24 | Millside Hospital Radio | Unitedkingdom | Sutton-in-ashfield | Kings Mill Hospital | Nottinghamshire | NG17 4JL | nhs.***** | 2002 | $243,269,799 | 4,500 | N/A | N/A | N/A |
| 25 | The Mission Group Public LIMITED Company | Unitedkingdom | Swimbridge | The Old Sawmills | Devon | EX32 0RN | themission.***** | 2006 | $241,255,097 | 1,054 | N/A | N/A | N/A |
| 26 | Wpp Samson LIMITED | Unitedkingdom | Herne Hill | Sea Containers House | London | SE1 9GL | wpp.***** | 2017 | $241,188,912 | 265 | N/A | N/A | N/A |
| 27 | Finecast LIMITED | Unitedkingdom | Saint Giles | 26 Red Lion Square | London | WC1R 4HQ | finecast.***** | 2017 | $240,499,633 | 114 | N/A | N/A | N/A |
| 28 | Ocean Bidco LIMITED | Unitedkingdom | Marylebone | 25 Kingly Street | London | W1B 5QB | N/A | 2012 | $238,385,065 | 287 | N/A | N/A | N/A |
| 29 | Vccp Group Llp | Unitedkingdom | London | Greencoat House | London | SW1P 1DH | vccp.***** | 2011 | $233,736,049 | 625 | N/A | N/A | N/A |
| 30 | Inmobi | Unitedkingdom | Moorgate | 235 High Holborn | London | WC1V 7DN | inmobi.***** | 2009 | $219,982,200 | 255 | N/A | N/A | N/A |
| 31 | Mindshare Media UK LIMITED | Unitedkingdom | London | Mindshare London Rose Court | London | SE1 9HS | mindshareworld.***** | 1997 | $209,862,261 | 725 | N/A | N/A | N/A |
| 32 | Wpp Brands (UK) LIMITED | Unitedkingdom | Herne Hill | 18 Upper Ground Borough | London | SE1 1RU | wpp.***** | 1944 | $206,145,392 | 939 | N/A | N/A | N/A |
| 33 | We Are Very Social LTD | Unitedkingdom | Finsbury | Alphabeta 14-18 Finsbury Square | London | EC2A 1BR | wearesocial.***** | 2010 | $196,081,249 | 1,154 | N/A | N/A | N/A |
| 34 | Astus UK LIMITED | Unitedkingdom | Marylebone | Davidson Building | London | WC2E 7HA | astusuk.***** | 2003 | $194,168,848 | 167 | N/A | N/A | N/A |
| 35 | All Response Media LIMITED | Unitedkingdom | Finsbury | Third Floor | London | EC1V 7EN | allresponsemedia.***** | 1995 | $171,665,260 | 212 | N/A | N/A | N/A |
| 36 | Ptarmigan Media LIMITED | Unitedkingdom | Rotherhithe | Bankside | London | SE1 0SW | N/A | 1992 | $164,578,356 | 149 | N/A | N/A | N/A |
| 37 | Mediaplus Group UK LTD | Unitedkingdom | Marylebone | First Floor, Waverley House | London | W1F 8GQ | totalmedia.***** | 1982 | $161,532,859 | 160 | N/A | N/A | N/A |
| 38 | Wmg Management Europe LIMITED | Unitedkingdom | Marylebone | 71-91 7th Floor | London | WC2B 4HN | N/A | 1998 | $157,521,962 | 347 | N/A | N/A | N/A |
| 39 | Omnicom Finance LIMITED | Unitedkingdom | Rotherhithe | 90-100 Southwark Street | London | SE1 0SW | omnicomfinance.***** | 1990 | $152,293,261 | 42 | N/A | N/A | N/A |
| 40 | Omd Group LIMITED | Unitedkingdom | Saint Giles | Fitzroy House | London | WC1E 7EY | omd.***** | 1987 | $151,200,624 | 914 | N/A | N/A | N/A |
| 41 | Iris Nation Worldwide LIMITED | Unitedkingdom | Moorgate | Thames Exchange | London | EC4R 1BE | iris-worldwide.***** | 2006 | $146,686,703 | 597 | N/A | N/A | N/A |
| 42 | Iris Worldwide Holdings LIMITED | Unitedkingdom | Moorgate | Thames Exchange | London | EC4R 1BE | iris-worldwide.***** | 2012 | $146,686,703 | 597 | N/A | N/A | N/A |
| 43 | Active International LIMITED | Unitedkingdom | Saint Giles | 1st Floor | London | WC1A 1EU | activeinternational.***** | 1990 | $139,509,369 | 46 | N/A | N/A | N/A |
| 44 | Pg Media Services LIMITED | Unitedkingdom | Shepherd'S Bush | Warwick Building | London | W14 8HQ | arcww.***** | 1943 | $137,585,235 | 910 | N/A | N/A | N/A |
| 45 | Fundamental Media LIMITED | Unitedkingdom | Moorgate | 3rd Floor Religare House | London | EC4N 6EU | fundamentalmedia.***** | 2003 | $137,242,687 | 165 | N/A | N/A | N/A |
| 46 | Konica Minolta Marketing Services LIMITED | Unitedkingdom | Saint Giles | 26-28 Bedford Row | London | WC1R 4HE | N/A | 2007 | $137,219,306 | 395 | N/A | N/A | N/A |
| 47 | Ocean Outdoor UK Holdco LIMITED | Unitedkingdom | Marylebone | 25 Argyll Street | London | W1F 7TU | N/A | 2023 | $136,585,129 | 114 | N/A | N/A | N/A |
| 48 | Seedtag Advertising | Unitedkingdom | Saint Johns Wood | 3rd and 4th Floor | London | EC1M3JB | N/A | 2017 | $130,084,326 | 339 | N/A | N/A | N/A |
| 49 | J. Walter Thompson U.K. Holdings LIMITED | Unitedkingdom | Herne Hill | Sea Containers House | London | SE1 9PD | jwt.***** | 1983 | $129,145,199 | 700 | N/A | N/A | N/A |
| 50 | THE&PARTNERS London LIMITED | Unitedkingdom | Saint Giles | The Charlotte Building, 17 Gresse Street | London | W1T 1QL | N/A | 2001 | $124,191,044 | 378 | N/A | N/A | N/A |
| 51 | Wpp Brands (europe) LIMITED | Unitedkingdom | Herne Hill | Sea Containers House | London | SE1 9PD | wpp.***** | 1980 | $122,149,384 | 126 | N/A | N/A | N/A |
| 52 | Halfords Media (UK) LIMITED | Unitedkingdom | Birmingham | One Chamberlain Square | Birmingham, West Midlands | B3 3AX | halfords.***** | 2004 | $120,441,768 | 643 | N/A | N/A | N/A |
| 53 | The Stepstone Group UK LTD | Unitedkingdom | Rotherhithe | Blue Fin | London | SE1 0TA | totaljobs.***** | 2001 | $118,705,153 | 518 | N/A | N/A | N/A |
| 54 | Diversified Agency Services LIMITED | Unitedkingdom | Strand | 239 Old Marylebone Road | London | NW1 5QT | dasglobal.***** | 1989 | $118,360,937 | 35 | N/A | N/A | N/A |
| 55 | Groupm UK Digital LIMITED | Unitedkingdom | Herne Hill | Sea Containers House | London | SE1 9GL | N/A | 1985 | $115,898,512 | 171 | N/A | N/A | N/A |
| 56 | Performance54 LIMITED | Unitedkingdom | West Wimbledon | 22 Worple Road | London | SW19 4DD | N/A | 2015 | $115,395,006 | 134 | N/A | N/A | N/A |
| 57 | Mediaplus UK (london) LTD | Unitedkingdom | Marylebone | Waverley House | London | W1F 8GQ | totalmedia.***** | 1982 | $114,929,420 | 96 | N/A | N/A | N/A |
| 58 | Agl UK Investments LIMITED | Unitedkingdom | Saint Johns Wood | 10 Triton Street Regent'S Place | London | NW1 3BF | N/A | 2020 | $113,173,259 | 2 | N/A | N/A | N/A |
| 59 | Zoopla LIMITED | Unitedkingdom | Rotherhithe | Copper Row | London | SE1 2LH | zoopla.***** | 2007 | $112,740,046 | 388 | N/A | N/A | N/A |
| 60 | Anomaly London Llp | Unitedkingdom | Clapton | Finsgate | London | EC1V 9EE | anomaly.***** | 2011 | $112,736,808 | 227 | N/A | N/A | N/A |
| 61 | Republic Of Media LIMITED | Unitedkingdom | Benchill | 5th Floor | Manchester, Greater Manchester | M2 7AQ | republicofmedia.***** | 2012 | $111,897,062 | 144 | N/A | N/A | N/A |
| 62 | Space & Time Media LIMITED | Unitedkingdom | Red Hill | 2nd Floor, Dean Park House | Bournemouth | BH1 1HL | N/A | 1991 | $110,266,926 | 193 | N/A | N/A | N/A |
| 63 | Adare International LIMITED | Unitedkingdom | Moorgate | 12th Floor Heron Tower | London | EC2N 4AY | iab.***** | 1982 | $110,248,942 | 257 | N/A | N/A | N/A |
| 64 | Primesight LIMITED | Unitedkingdom | Saint Giles | Met Building | London | W1T 2BU | primesight.***** | 1984 | $109,663,185 | 234 | N/A | N/A | N/A |
| 65 | Mccann-Erickson Advertising LIMITED | Unitedkingdom | Butley Town | Bonis Hall Lane | Cheshire East | SK10 4EF | mccann.***** | 1978 | $106,813,618 | 250 | N/A | N/A | N/A |
| 66 | Ocean Outdoor UK LIMITED | Unitedkingdom | Marylebone | Regent Arcade House | London | W1F 7TS | oceanoutdoor.***** | 2004 | $103,844,706 | 126 | N/A | N/A | N/A |
| 67 | Evolve Ooh LIMITED | Unitedkingdom | Marylebone | 130 Shaftesbury Avenue | London | W1D 5EU | N/A | 2018 | $103,222,275 | 59 | N/A | N/A | N/A |
| 68 | John Ayling And Associates LIMITED | Unitedkingdom | Marylebone | 27 Soho Square | London | W1D 3QR | jaa-media.***** | 1978 | $102,137,508 | 64 | N/A | N/A | N/A |
| 69 | John Ayling Group LIMITED | Unitedkingdom | London | 2 Leman Street | London | E1W 9US | N/A | 2022 | $102,137,508 | 64 | N/A | N/A | N/A |
| 70 | Jakala UK LIMITED | Unitedkingdom | Moorgate | C/o Arch | London | EC2N 4BQ | N/A | 2003 | $102,026,340 | 63 | N/A | N/A | N/A |
| 71 | M&C Saatchi World Services Llp | Unitedkingdom | Marylebone | 34-36 Golden Square | London | W1F 9EE | mcsaatchi.***** | 2011 | $101,462,302 | 230 | N/A | N/A | N/A |
| 72 | Havas Programmatic Hub LIMITED | Unitedkingdom | Saint Johns Wood | 3 Pancras Square | London | N1C 4AG | havasworldwide.***** | 2014 | $100,536,201 | 2 | N/A | N/A | N/A |
| 73 | Arena Media LIMITED | Unitedkingdom | Saint Johns Wood | 3 Pancras Square | London | N1C 4AG | havasworldwide.***** | 2005 | $97,261,816 | 6 | N/A | N/A | N/A |
| 74 | What's Possible Marketing Group LIMITED | Unitedkingdom | Upper Holloway | 94 White Lion Street | London | N1 9PF | thespecialistworks.***** | 2018 | $92,376,700 | 126 | N/A | N/A | N/A |
| 75 | George P. Johnson (united Kingdom) LIMITED | Unitedkingdom | Rotherhithe | 53 Great Suffolk Street | London | SE1 0DB | gpj.***** | 1987 | $91,795,877 | 272 | N/A | N/A | N/A |
| 76 | Publicis Media LIMITED | Unitedkingdom | Shepherd'S Bush | 5th Floor, 2 Television Centre | London | W12 7FR | publiciscommerce.***** | 2001 | $90,689,019 | 47 | N/A | N/A | N/A |
| 77 | Miroma International LTD | Unitedkingdom | London | Elsley Court | London | W1W 8BE | N/A | 2002 | $89,491,501 | 154 | N/A | N/A | N/A |
| 78 | Mother London LIMITED | Unitedkingdom | Stepney | The Biscuit Building | London | E2 7DD | motherlondon.***** | 1996 | $89,314,546 | 226 | N/A | N/A | N/A |
| 79 | Lindar Media LIMITED | Unitedkingdom | Saint Albans | Queens House | Hertfordshire | AL1 3HZ | lindar.***** | 2014 | $87,435,343 | 77 | N/A | N/A | N/A |
| 80 | Zenith UK (media) LIMITED | Unitedkingdom | Shepherd'S Bush | Zenith UK 5th Floor, 2 Television Centre | London | W12 7FR | zenithoptimedia.***** | 1985 | $85,476,773 | 521 | N/A | N/A | N/A |
| 81 | Digital Cinema Media LIMITED | Unitedkingdom | Saint Johns Wood | 350 Euston Road | London | NW1 3AX | dcm.***** | 1996 | $82,592,522 | 66 | N/A | N/A | N/A |
| 82 | Optimise Media Group LIMITED | Unitedkingdom | Eaton | Exchange Street Buildings | Norfolk | NR2 1DP | optimisemedia.***** | 2001 | $81,143,384 | 134 | N/A | N/A | N/A |
| 83 | The Creative Engagement Group LTD | Unitedkingdom | Castlefield | Merchants Warehouse | Manchester, Greater Manchester | M3 4LZ | N/A | 1976 | $80,752,194 | 350 | N/A | N/A | N/A |
| 84 | Apx Trading LIMITED | Unitedkingdom | London | 1st Floor,2 Television Centre | London | W12 7FR | N/A | 1984 | $80,307,807 | 3 | N/A | N/A | N/A |
| 85 | The Specialist Works LIMITED | Unitedkingdom | Upper Holloway | 94 White Lion Street | London | N1 9PF | thespecialistworks.***** | 2002 | $80,246,793 | 370 | N/A | N/A | N/A |
| 86 | The Kite Factory Group LIMITED | Unitedkingdom | Saint Giles | 55-59 New Oxford Street | London | WC1A 1BS | thekitefactorymedia.***** | 2001 | $79,646,373 | 98 | N/A | N/A | N/A |
| 87 | Williams Lea LIMITED | Unitedkingdom | Belle Isle | Darwin House, Leeds Valley Park | Leeds, West Yorkshire | LS10 1AB | N/A | 1901 | $79,168,565 | 1,168 | N/A | N/A | N/A |
| 88 | The Kite Factory LIMITED | Unitedkingdom | Saint Giles | Second Floor | London | WC1A 1BS | thekitefactorymedia.***** | 2014 | $79,072,197 | 98 | N/A | N/A | N/A |
| 89 | Peoplescout LIMITED | Unitedkingdom | Saint Giles | 265 Tottenham Court Road | London | W1T 7RQ | tmpw.***** | 1965 | $78,906,479 | 275 | N/A | N/A | N/A |
| 90 | Uncommon Creative Studio LIMITED | Unitedkingdom | Finsbury | 102-108 Clerkenwell Road | London | EC1M 5SA | N/A | 2021 | $77,499,739 | 146 | N/A | N/A | N/A |
| 91 | Bauer Media Outdoor Holdings LIMITED | Unitedkingdom | Marylebone | 33 Golden Square | London | W1F 9JT | clearchannel.***** | 1998 | $77,217,367 | 27 | N/A | N/A | N/A |
| 92 | Saatchi & Saatchi Group LTD | Unitedkingdom | Shepherd'S Bush | 1st Floor 2 Television Centre | London | W12 7FR | saatchi.***** | 1970 | $77,059,597 | 327 | N/A | N/A | N/A |
| 93 | Isobar | Unitedkingdom | Rotherhithe | South Bank Student Union, Keywor | London | SE1 6NG | N/A | 2011 | $77,055,880 | 1,500 | N/A | N/A | N/A |
| 94 | Dazn Media Channels LIMITED | Unitedkingdom | Shepherd'S Bush | 12 Hammersmith Grove | London | W6 7AP | dazngroup.***** | 2005 | $76,779,150 | 291 | N/A | N/A | N/A |
| 95 | Mccann Manchester LIMITED | Unitedkingdom | Butley Town | Bonis Hall | Cheshire East | SK10 4EF | mccann.***** | 1986 | $76,273,891 | 370 | N/A | N/A | N/A |
| 96 | Bray Leino LIMITED | Unitedkingdom | Atherington | The Old Sawmills | Devon | EX32 0RN | brayleino.***** | 1978 | $75,652,928 | 217 | N/A | N/A | N/A |
| 97 | Aka Nyc LIMITED | Unitedkingdom | Saint Giles | 115 Shaftesbury Avenue Cambridge Circus | London | WC2H 8AF | akauk.***** | 1999 | $74,994,000 | 86 | N/A | N/A | N/A |
| 98 | Aka Promotions LIMITED | Unitedkingdom | Saint Giles | 117 Shaftesbury Avenue | London | WC2H 8AF | akauk.***** | 1997 | $74,644,047 | 302 | N/A | N/A | N/A |
| 99 | Gumtree.com LIMITED | Unitedkingdom | Herne Hill | We Work UK Ltd | London | SE1 7ND | N/A | 2000 | $74,298,744 | 119 | N/A | N/A | N/A |
| 100 | Intermarketing Agency LIMITED | Unitedkingdom | Collingham | The Malt House | Leeds, West Yorkshire | LS10 1LJ | ima.***** | 1989 | $74,080,618 | 344 | N/A | N/A | N/A |