The following list shows all the companies that are in the game.
| Companies List | |||
| Pos. | Company Name | Awards | Total Worth |
| 12301 | One Silence | £ -4,074 | |
| 12302 | One to Many. | £ 4,976,234 | |
| 12303 | One United | £ 5,379,005 | |
| 12304 | one1 | £ 3,058,084 | |
| 12305 | OneNation | £ 45,456 | |
| 12306 | oneone | £ 18,206,569 | |
| 12307 | Oner | £ 10,516,756 | |
| 12308 | OneStopEnvelopeShoppe | £ -38,952 | |
| 12309 | Onion of Arabia | £ 11,458,256 | |
| 12310 | Onions | £ 56,031,337 | |
| 12311 | onions inc | £ 46,832,459 | |
| 12312 | ONLINE GAMES | £ 120,242,830 | |
| 12313 | Only Bombs Allowed | £ 57,741,277 | |
| 12314 | Only Fools and Horses | £ 859,719,219 | |
| 12315 | only me | £ 50,000 | |
| 12316 | only me inc | £ 133,078,068 | |
| 12317 | Onomatopoeias | £ 939,660 | |
| 12318 | Onshore Money | £ 104,918,400 | |
| 12319 | Ontara | £ 79,736,570 | |
| 12320 | Ontario | £ 85,260,376 | |
| 12321 | ontheblock | £ 6,402,837 | |
| 12322 | Onyx | £ 429,592 | |
| 12323 | OO7 | £ 5,508,861 | |
| 12324 | Ooglaigh na Heireann | £ 240,713,877 | |
| 12325 | oohyeaa | £ 50,844,745 | |
| 12326 | Oolacile-01 | £ 2,954,344 | |
| 12327 | oOoOo | £ 31,474,744 | |
| 12328 | oooooo | £ 5,505,528 | |
| 12329 | OOOoooOOO | £ 614,697 | |
| 12330 | oooPPPooo | £ -53,065 | |
| 12331 | oops | £ 965,477 | |
| 12332 | ooz | £ 320,966,832 | |
| 12333 | Opal Opal | £ 5,502,194 | |
| 12334 | Opec | £ 273,634,128 | |
| 12335 | Opel Dire | £ 5,505,993 | |
| 12336 | OpEn FoR BuIsNeSs | £ 5,785,269 | |
| 12337 | Operation Racoon City | £ 4,748,173 | |
| 12338 | Operations | £ 8,189,228 | |
| 12339 | Ophthalmology | £ 45,575,639 | |
| 12340 | opiates | £ 10,578,986 | |
| 12341 | Opinion | £ 389,953,431 | |
| 12342 | OPiuM | £ 115,856,941 | |
| 12343 | Oppa Gangnam Style | £ 65,242,420 | |
| 12344 | Oppenheim | £ 51,959,450 | |
| 12345 | Oppertunity | £ 458,210,505 | |
| 12346 | Opportunity | £ 11,354,079 | |
| 12347 | Opposition | £ 761,831,311 | |
| 12348 | Oppression | £ 416,055,267 | |
| 12349 | optical | £ 398,873,238 | |
| 12350 | Optimal Flames | £ 168,931,399 | |
| 12351 | Optimum Nutrition | £ -3,018,246 | |
| 12352 | Optimus Inc. | £ -2,482,292 | |
| 12353 | Options | £ 84,494,650 | |
| 12354 | Opus Dei | £ 694,720,428 | |
| 12355 | opus technology | £ 35,372,824 | |
| 12356 | Oracle | £ 5,067,108 | |
| 12357 | Orange | £ 24,725,264 | |
| 12358 | Orange Aftershock | £ 67,681,186 | |
| 12359 | Orange Castle | £ 615,362 | |
| 12360 | Orange Creatine | £ 6,196,167 | |
| 12361 | Orange Jelly | £ 6,594,926 | |
| 12362 | Orange Jooze | £ 1,261,621 | |
| 12363 | Orange Jooze 3 | £ 50,000 | |
| 12364 | Orange Jooze2 | £ 795,888 | |
| 12365 | Orange Jooze4 | £ 50,000 | |
| 12366 | Orange Jooze5 | £ 50,000 | |
| 12367 | Orange Paint | £ 97,288,036 | |
| 12368 | Oranginal | £ 4,103,756 | |
| 12369 | oranje | £ 4,966,784 | |
| 12370 | Orbital | £ 54,539,946 | |
| 12371 | Orbital Bombardment | £ 854,964,581 | |
| 12372 | Orchids R Us Ltd | £ 39,331,588 | |
| 12373 | orcs | £ 2,515,547,748 | |
| 12374 | Orcustra | £ 702,800 | |
| 12375 | Order | £ 176,233,665 | |
| 12376 | Oregon | £ 111,775,168 | |
| 12377 | OREO | £ 64,657,012 | |
| 12378 | Org | £ 18,286,924 | |
| 12379 | Organic Beaver | £ 49,155,560 | |
| 12380 | Organics Ltd | £ 105,054,559 | |
| 12381 | Organised Crime | £ 17,216,443 | |
| 12382 | Organized Crime | £ 62,808,878 | |
| 12383 | Orgia Co. | £ 4,887,593 | |
| 12384 | Orgy | £ 4,311,652,261 | |
| 12385 | Origin yartley | £ 37,041,694 | |
| 12386 | Original 16 | £ 132,618,089 | |
| 12387 | Original Sin | £ 141,442,446 | |
| 12388 | Originality | £ 1,357,128,017 | |
| 12389 | Origins | £ 63,035,912 | |
| 12390 | Orion | £ 47,648,728 | |
| 12391 | orm | £ 413,783,803 | |
| 12392 | orming | £ 56,130,756 | |
| 12393 | OronzoMafia | £ 560,700 | |
| 12394 | Orphans Court | £ 18,746,350 | |
| 12395 | Orphic Co. | £ 4,423,125 | |
| 12396 | Orquinox Co. | £ 1,119 | |
| 12397 | Orricks IT Services | £ 15,082,611 | |
| 12398 | Ortcaj | £ 77,296,813 | |
| 12399 | Orthanc Inc. | £ 147,448,563 | |
| 12400 | Osaka | £ 5,504,057 | |
