Moustakas will receive a $3-million buyout from the Brewers. He is ineligible to receive a qualifying offer because he got one - which he declined - during the 2017-18 offseason.
The 31-year-old was a free agent last winter but found no suitors during an extended stay on the open market. He finally re-signed with Milwaukee in February, shortly after spring training had begun.
Moustakas proceeded to have a career year in 2019. He slashed .254/.329/.516 with 35 homers, 30 doubles, and 87 RBIs over 143 games, and was named an All-Star for the third time.
He also proved surprisingly versatile for the Brewers, as the natural third baseman spent a large portion of the year playing second base. He took to the new position well, tallying an even zero defensive runs saved in 359 2/3 innings at the keystone.
Moustakas, a nine-year veteran, has hit 182 home runs over 1,131 career games with the Brewers and Kansas City Royals. He won a World Series with Kansas City in 2015.
The Brewers also announced that first baseman/outfielder Tyler Austin and utility man Cory Spangenberg have elected for free agency. Both players had been outrighted by the team to Triple-A San Antonio.