Seiko Okamoto (岡本 聖子, Okamoto Seiko) (born 14 March 1978) is a Japanese former professional tennis player.

Okamoto took part in the 2006 Bangalore Open but lost in the first round of singles qualifying, and the first round of doubles, alongside Ryōko Fuda.

She has stated that her favorite surface to play on is hardcourt.

In her career, Okamoto won one doubles title on the WTA Tour, as well as two singles and 15 doubles titles on the ITF Women's Circuit.

This biographical article relating to Japanese tennis is a stub.