Mookie Betts is on the move, but he ain't leaving the Dodgers ... TMZ Sports has learned he's now got a giant new house to live in!!

Real estate sources tell us ... the MLB superstar just copped a $15 million pad this month in Encino -- just a few miles away from Dodger Stadium.

We're told the place is sweet ... featuring super sleek and modern lines.

Unclear of how many beds, baths and bells and whistles it all officially comes with -- though it sits on 2 acres ... so there's plenty of room for Mookie to work on his base-running skills if he wants.

Of course, Mookie's been living in L.A. for a while now -- he was traded to the City of Angels prior to the 2020 season -- though after having his second child earlier this year ... seems he was in need of an upgrade.

We're told Craig Knizek and Scott Gorelick of The Agency repped the seller ... while Morgan Trent of AKG | Christie's International Real Estate repped the baseball player in the sale.

Congrats on the new place, Mookie!!!