Kiyomi Niwata (Japanese: ????, born 10 December 1970 in Ushiku, Ibaraki Prefecture) is a professional triathlete from Japan, triple Olympian (Sydney, Athens, Beijing), multiple-time National Champion (2004, 2005, 2006), and an Asian Aquathlon Champion and Oceanian Triathlon Champion of the year 2009.
Kiyomi Niwata and Anja Dittmer are the only triathletes who took part in all three Olympic triathlons.
In Sydney and in Athens, Niwata placed 14th, in Beijing, 9th.
She is coached by Col Stewart.