Kentaro Hayashi joined Verdy Kawasaki (Currently Tokyo Verdy) in 1995 after graduating from Toin Gakuen High School and Komazawa University.
He played very well as a key player of the team which was the strongest team at that time in his first year and won the J-League 2nd stage and the Emperor's Cup. He was also selected for the Japan national team in 2015.
Kentaro was on loan to Vissel Kobe in 1998.
Then returned to Verdy Kawasaki in 1999 and became a vital central midfielder and contributed to win the Emperor's Cup in 2004.
After played for Ventforet Kofu from 2006 to 2009 season, Kentaro decided his retirement as a player.
Then he has started his coaching career and managed The University of Tokyo Association Football Club and Tokyo United FC as a coach and a sports director.
In 2018 he returned to Vissel Kobe as a coach. 
After taking part in a training course at FC Barcelona as a coach he worked as an assistant coach at Vissel Kobe and managed the team as an interim manager in 2018.
Also he worked as a coach with some managers like Juanma Lillo, Atsuhiro Miura and Takayuki Yoshida at Vissel Kobe.
Kentaro has been appointed a manager of Gainare Tottori in 2024.

●International
・International match: 2 appearances

●Titles（club / national team）
・1995  J.League Division 1, 2nd stage 
・1996  The Emperor's Cup
・2004  The Emperor's Cup