An All-Star in 2021, Walsh is batting just .119 with one home run and five RBIs in 28 games this season.
Walsh batted .277 with 29 homers and 98 RBI during his All-Star season but slumped badly last season while battling thoracic outlet syndrome.
He also disclosed during spring training that he was dealing with neurological issues and he missed the first 46 games of this season while getting treatment. He returned to the majors on May 20.
Walsh, who turns 30 on Sunday, is a career .243 hitter with 55 homers and 178 RBIs in 353 games over five seasons with the Angels.
In another corresponding transaction, the Angels transferred rookie right-hander Ben Joyce (elbow) to the 60-day injured list.