O
- Octavo Systems
- Oculus
- ODU
- OEG Relays / TE Connectivity
- OHM Americas
- Ohmite
- OK Industries (Jonard Tools)
- OKdo
- OLC Inc.
- Ole Wolff Electronics Inc.
- Olimex Ltd.
- Olmatic
- Olympus
Omnetics
OmniPreSense- OmniVision Technologies
- Omron Automation
- Omron Electronic Components
- OMS Motion
- ON Semiconductor
- OncQue
- Ondrives.US Corp
Omnetics
OmniPreSense- OneSimCard
- Onion Corporation
- OnsemiView Product
- Onyx Healthcare USA
- On-Shore Technology, Inc.
- Oplink, a Molex company
- Opsero
- OptConnect
- Optek Technology/TT Electronics
- Optical Zonu Corporation
- OptiFuse
- Optiks Mechatronics Pvt. Ltd.
- Optilab
- Optilumen Inc.
- Optimus Logic
- Option NV
- Optiwave
- Opto 22
- Opto Diode Corporation
- Optrex / KYOCERA
- Opulent
- Orbel
- Orient Display
- OriginGPS
- ORing
- Orion Fans
- Oscium
- Osela
- OSEPP Electronics
- Oshino Lamps
- OSI Optoelectronics
- OSRAM Opto Semiconductors / ams OSRAM
- OStream
- Othernet
- OTTE Tape
- Otto DIY
- Oupiin
- OVERCONN SRL
- Overview
- OWON Technology Lilliput Electronics
- Ox Tools
- Oyen Digital
- O'Reilly Media, Inc.
- O.C. White Co.