Keitaro Hoshino (born 1969-08-14 in Yokohama, Kanagawa, Japan) is a flyweight boxer.
Hoshino turned pro in 1988 and captured the WBA minimumweight title with a decision win over Joma Gamboa in 2000. He defended the belt once before losing it by split decision to Chana Porpaoin in 2001. He recaptured the vacant WBA minimumweight title with a decision win over Gamboa in 2002, but lost the belt in his first defense to Noel Arambulet.
| Preceded by Joma Gamboa |
WBA Minimumweight Champion 2000 Dec 6 – 2001 Apr 16 |
Succeeded by Chana Porpaoin |
| Preceded by Yutaka Niida Retired |
WBA Minimumweight Champion 2002 Jan 29 – 2002 Jul 29 |
Succeeded by Noel Arambulet |