Seiko is a word which has several meanings:
- , a brand name for Japanese clock and watch company Seiko Holdings Corporation (formerly K. Hattori & Co., Ltd., aka Hattori Tokeiten, Hattori Seiko or Seiko Corporation)
- , a Japanese corporate group consisting of three independent companies Seiko Holdings Corporation, Seiko Instruments Inc. and Seiko Epson Corporation
- , a Japanese given name, almost exclusively used for female. People that have the name include:
- Seiko SA, a defunct football club in Hong Kong
- Seiko Films, a movie outfit in the Philippines