'KUWTK' Star Todd Kraines Proposes to Pregnant Girlfriend Joy Corrigan

Joy Corrigan's leveling up -- 'cause TMZ's learned her man Todd Kraines didn't just put a bun in the oven, but he's popped the question too!

Sources tell us Todd the Sports Illustrated model got engaged at Calamigos Guest Ranch in Malibu on Sunday. We're told she thought they were just going on a chill staycation but her boo had other plans for her ... as you can see in these exclusive pics!

We're told Joy got all dolled up thinking it was just a dinner date -- but when they rolled up in a golf cart and she found herself wandering through the woods ... boom! They turn a corner, and it's flowers everywhere. That's when it clicked for Joy.

We're told Todd poured his heart out, telling Joy the last 6 months with her have been the wildest ride but the best of his life … and then, yep, he dropped to one knee and popped the big question.

The two actually went ring shopping with his parents a few months back, so Joy knew it was coming -- just not when. After the proposal, they capped the night off with a romantic dinner and broke the news to their families.

The engagement news stacks right on top of their baby joy -- TMZ broke the story ... Joy's pregnant with Todd's baby. We got Todd out in L.A. on Tuesday, where he gushed about their little one on the way.