Kyle Kuzma will leave Los Angeles for D.C. as a single man ... TMZ Sports has learned the former Lakers star and his model GF, Winnie Harlow, have broken up.

Sources tell us Kuzma -- who was just officially traded to the Washington Wizards from L.A. earlier this month -- split with Harlow about a week ago.

We're told, though, it was a completely amicable breakup ... and, in fact, we're also told the two have been friendly with each other since the split.