After wrestling at the 1984 Olympics, Hiroshi Hase turned professional in 1986 and joined Carlos Colón’s World Wrestling Council in Puerto Rico. He then moved to Calgary, Canada where he was with Stampede Wrestling. By the end of 1987 he returned to Japan, joining New Japan Pro Wrestling (NJPW), with which he wrestled from 1987-96. He was twice the International Wrestling Grand Prix junior-heavyweight champion (1987, 1989). In 1989 Hase trained in Russia, learning sambo and one of his signature moves, the uranage. In 1994 Hase won the WCW International World Heavyweight Championship, but held it for only eight days.
In July 1995 Hase was elected to the Japanese House of Councilors as Senior Vice-Minister of Education, Culture, Sports, Science and Technology. His last bout with NJPW was shortly thereafter, in January 1996. He returned to wrestling in November 1996, however, this time with All-Japan Pro Wrestling (AJPW), while he continued to serve in the Japanese Diet. He lost his seat in the Diet in 2009, but was then re-elected from a different block. He retired from wrestling in 2006 and, one week later, was elected into the Wrestling Observer Newsletter Hall of Fame. In 2007 Hase became chairman of the Pro Wrestling Federation in Japan, holding that position until 2013.