After initially missing out on the Opening Day roster, on March 30, 2023, the Brewers announced that Wiemer was promoted to the major leagues.
On April 1, Wiemer hit a double in his major league debut against the Chicago Cubs at Wrigley Field on the first pitch he saw.
[10] On April 5, Wiemer hit his first major league home run in a win over the New York Mets at American Family Field.
[15] On July 30, 2024, the Brewers traded Wiemer, Jakob Junis, and cash considerations to the Cincinnati Reds in exchange for Frankie Montas.
On November 22, 2024, the Reds traded Wiemer and Jonathan India to the Kansas City Royals in exchange for Brady Singer.