The 31-year-old striker arrived at St Andrew’s from Rennes last summer on a three-year contract and scored three goals in 31 appearances during the 2025/26 campaign.
"We’re excited to welcome Kyōgo to the LA Galaxy and to Los Angeles,” said LA Galaxy General Manager Will Kuntz.
“He brings a wealth of experience having played matches with Japanese National Team, in the UEFA Champions League, and in some of the best domestic leagues in Europe.
“We’re thrilled to add a player of his caliber, goal scoring ability, and diverse experience to our group and look forward to the impact he will make on and off the field."
Furuhashi previously enjoyed a prolific spell at Celtic, scoring 85 goals and providing 19 assists in 165 appearances between 2021 and 2025.
He helped the Scottish giants win eight domestic trophies, including four Premiership titles, and claimed the Golden Boot and Player of the Year awards after scoring 27 league goals in 2022-23.