Seiko is a brand name for Japanese clock and watch company Seiko Group Corporation.

Seiko may also refer to:

• Seiko Group, in former days, a Japanese corporate group consisting of three independent companies including
  • Seiko Group Corporation (f/k/a K. Hattori, Hattori Seiko, and Seiko Holdings)
  • Seiko Instruments (f/k/a Daini Seikosha, Seiko Instruments & Electronics)
  • Seiko Epson (f/k/a Suwa Seikosha)
• Seiko Films, a movie outfit in the Philippines
• Seiko SA, a defunct football club in Hong Kong
• Silver Seiko Ltd., knitting machine and typewriter company (1952-2011)

• Seiko (given name), a name and a list of people with the name
• Seiko (album), a 1990 album by Seiko Matsuda