John, Chrissy and their 4 kids hit up the pink mansion, ahead of the release of the new "Barbie" film. It's been decked out from the foundation to the roof in everything B&K.

Ken was the host, showing the fam all the bells and whistles. Their daughter, Luna, lounged by the pool in a pink chair.

Miles suited up in Ken's cowboy hat and boots and danced a bit inside what looks like a dressing room -- Barbie-inspired, of course.

The flick opens in just under 3 weeks, and the marketing has been pretty spectacular. The mansion will be available to the public on Airbnb for a few days as part of the promotion, but John and Chrissy got an early "booking."

As you know, Chrissy just had a baby, and they welcomed their 4th kid via surrogate last month.