| Obambu S.A.R.L. | Paris |
| OBCM | |
| Obeo | |
| Obilog | Haute-Savoie |
| Obiou Société d’Électronique | Isère |
| Obiwane | Dordogne |
| Obiz | |
| Object'Ive | Paris |
| Objectif Libre | Haute-Garonne |
| Objectif Micro | Rhône |
| Objectif Multimedia | Manche |
| Objectis | Paris |
| Objectware | |
| Objetconnecte.com | Paris |
| Objis | Métropole de Lyon |
| Obratori | |
| OBSYS | Maine-et-Loire |
| Obvious Technologies | |
| Obvy | |
| OC3 Network | Hérault |
| OCamlPro | |
| Océane Consulting | Paris |
| Océane Télécom | Loire-Atlantique |
| Oceanet Technology | Loire-Atlantique |
| Oceatech | Haute-Garonne |
| OcenWorld | Hérault |
| OCI | Bas-Rhin |
| Ocode | |
| Oconnection | |
| Ocreat | Seine-Saint-Denis |
| OCS Technology | Oise |
| OCSI Group | |
| Octave Octave | Paris |
| Octet Informatique | Haute-Savoie |
| Octet Plus | Val-d'Oise |
| Octets S.A.R.L. | Haute-Savoie |
| Octime | Hauts-de-Seine |
| Octo Technology | Paris |
| Octobat S.A.S. | |
| October | Paris |
| Octofax S.A.R.L. | Morbihan |
| Octogone S.A.S. | Haut-Rhin |
| Octolo.tech | |
| Octopuce | Paris |
| Octopush | Bouches-du-Rhône |
| OcTos e-comm Network | Yvelines |
| OCUS | |
| Oddifact | |
| ODDO BHF | |
| ODEIS | Pyrénées-Atlantiques |