Saito soon jumped to All Japan Pro Wrestling (AJPW), where he formed the "Calgary Hurricanes" with Shunji Takano. He competed in the All Japan World Junior Heavyweight Championship tournament in July 1986 where he defeated Brad Armstrong in the final to become the first World Junior Heavyweight Champion. After four months as champion, Saito lost the title to former stablemate Kuniaki Kobayashi.[5]
Saito joined the group known as the Raging Staff and soon won the IWGP World Tag Team Championship with Super Strong Machine from Hiroshi Hase and Kensuke Sasaki in December 1990, which they held for 3 months until Hase and Sasaki won them back in March 1991.[6][7] After Raging Staff dispersed, Saito joined Team Wolf with Masahiro Chono and Hiroyoshi Tenzan, and was later part of nWo Japan.
In 2006, after spending many years in relegation, Saito quit New Japan once again and began appearing for Tatsumi Fujinami's Muga promotion.
Hiro Saito was the first Japanese wrestler to use and popularize the "diving senton", or seating splash off the top rope, in matches. He is not related to Masa Saito, despite sharing name and appearance (aside from the blond hair); Hiroyuki shortened his name to "Hiro" to copy him (since Masa Saito's real name is Masanori) and also as a meaning of sharing fortune ("good luck").