Robin Thicke, April Love Geary Finally Marry in Los Cabos, Mexico

Robin Thicke and April Love Geary finally said "I do" -- and TMZ’s learned it's after the ceremony had a little plot twist thanks to some moody weather that made them shuffle things around.

Sources tell TMZ ... the vows went down beachside Friday, right outside Las Ventanas luxury resort in Cabo -- after a little rain threatened to overshadow their earlier spotlight. Geary stunned in beautiful white dress, while Thicke rocked a swanky tux.

We’re told their 3 kids were front and center for the big moment -- a full-circle vibe, since Robin and April always planned to wait until the little ones were old enough to soak it all in.

In fact, Thicke is seen walking down the aisle to Leonard Cohen's "Hallelujah" in a fresh pair of shades, holding hands with his son -- who carried a box labeled "Ring Security." Thicke lifted it up and proudly declared, "We have secured the ring, everybody!"

The newlyweds danced the night away ... with Thicke and Geary sweetly twirling each other on the dance floor.

Robin’s in a sweet spot in life right now -- and there was a load of joy around this wedding, which went down with a star-studded guest list to match, just like we told you before.

Leo DiCaprio, Usher, and Ken Jeong were all in the mix -- and the Cabo celebrations are far from over, with the party rolling on 'til Sunday.

Robin and April have been going strong since 2014 -- he first popped the question on Christmas 2018, then doubled down with a second proposal earlier this month at Cannes.