He has previously played in MLB for the San Francisco Giants, Cincinnati Reds, and Baltimore Orioles.

[4][5] Slater made his professional debut in 2014 with the Arizona League Giants and was promoted to the Salem-Keizer Volcanoes after two games.

[7] He spent 2015 with the San Jose Giants and Richmond Flying Squirrels where he posted a .294 batting average with three home runs and 47 RBIs in 114 games between both teams.

[8] After the season, the Giants assigned him to the Scottsdale Scorpions of the Arizona Fall League (AFL).

In 109 games between both teams, he posted a combined .305 batting average with 18 home runs and 67 RBIs.

[12] Avoiding arbitration, Slater and the Giants agreed on a $1.15 million salary for the 2021 season.

[17] On January 13, 2023, Slater agreed to a one-year, $3.2 million contract with the Giants, avoiding salary arbitration.

Following the season on October 11, Slater underwent arthroscopic surgery to remove a bone spur from the back of his right elbow.

[19] On July 7, 2024, the Giants traded Slater to the Cincinnati Reds in exchange for Alex Young.

On November 18, 2024, Slater signed a one-year, $1.7 million contract with the Chicago White Sox.