Robin Thicke -- Party's Over ... I'm Chillin' Out in Malibu

The evolution of Robin Thicke continues … TMZ has learned the singer just dropped $2.4 million on a quiet equestrian compound in Malibu.

The 4-bedroom mid-century home is a real change of pace -- boasting ocean views, 60 fruit trees, and a 4-stall horse corral ... it's a long ways from the party pad where he and Paula Patton used to live.

The new place doesn't even have a pool. On the other hand, it was recently retrofitted for earthquake safety ... so, his insurance premiums will be lower. Soooo sexy.

If you recall, Thicke sold his West Hollywood crib for nearly $5 million -- an astounding $1.9 mil more than his asking price. Looks like Robin's finally mellowing out.