- OPPIO GROUP
- Opple Lighting Co., Ltd.
- OPPS architettura
- OPR - Orlando Pereira Ribeiro
- opra costruzioni
- opra22
- Oprandi Architetti
- OPRAR
- oprar
- OPS
- OPSdesign
- opsira GmbH
- Opsis Architects
- Opstalt
- OptaLED Suisse Sàrl
- OPTEA
- OPTELMA Architectural Lighting
- OPTICOS, SRL
- Optics Lighting & Controls - Calgary
- Optics Lighting & Controls - Edmonton
- Optigreen internazionale AG
- Optiled Lighting International Ltd.
- OPTILUM
- Optima Energia
- optima impianti
- optima italia
- OPTIMA System
- optimak group
- Optimized Group
- Optimum Aydinlatma
- Optimum Surfaces
- OPTION D'INTERIEUR
- Opto Light S.L.U
- Optogan GmbH
- Optoled Elektrik Elektronik Enerji Sist. ve Ins. San. Ltd. Sti.
- OPTOLED Lighting GmbH
- Optris
- Opulent Techno Pte. Ltd.
- Opuntia.lab
- OPUR srl
- OPUS
- OPUS
- OPUS
- Opus 5
- OPUS atelier
- OPUS CERTUM
- Opus Gas Metano
- opus med