Kengo Yamazaki (山﨑 謙吾, Yamazaki Kengo, born 30 July 1992 in Ibaraki Prefecture) is a Japanese retired track and field sprinter who specialized in the 400 metres. His personal best in the event was 46.00 seconds set in Tokyo in 2013. He competed in the 4 × 400 metres relay at the 2013 World Championships.