- office now-here
- Office of architecture Patriarche
- office Pirelli
- Office Polytek Engineering Company Ltd.
- Office Prada
- Office PRESS
- Office PRPC Engenheiros
- Office Quadras Baumanagement Ltd.
- Office RSI
- office spaceworkers
- OFFICE TATEMONO
- Office VK Engineering
- Office X
- Office Yellow
- OFFICIAL EDIL GIARDINA
- Official Inalco
- Official Maytoni
- Official Oskad
- Officina Archetipo Architettura & Interior Design
- officina creativa spazio U.Nic
- officina del ferro officina del ferro srl
- Offner Keren
- Offredi Giovanni
- offredi marco
- Oficina d'Arquitectura a Mallorca OAM
- Oficina de Arquitectura PLTFRMA
- Oficina Local de Arquitectura OLA
- Ofori-Frimpong Laveane
- Ofosu-Ennin Kofi
- Ofria Luca
- Og Max
- Ogata Shinichiro
- Ogawa Bunzo
- Ogawa Hironaka
- Ogawa Shinichi
- Ogbuagu Chidi
- Ogg Graeme
- Oggian Marco