Antti Sainio (born 17 May 2005) is a Finnish hurdler.

[1] He won the silver medal at the 2023 European Athletics U20 Championships over 400 metres hurdles.

[2] In 2024, Sainio recorded the a new U20 Finnish record of 49.91 seconds for the 400 metres hurdles.

He qualified for the final of the 400m hurdles at the 2024 World Athletics U20 Championships with a new Finnish age group record of 49.36 seconds.

[3][4] Running in the final, he won the bronze medal with a time of 49.61 seconds.