Justin Verlander and Kate Upton are getting the martial house ready to go ... because they just locked up a sweet Bev Hills mansion for $5.475 mil ... and it comes with it's own private tennis court!
The Detroit Tigers pitcher proposed to his supermodel girlfriend back in May -- and we're told the house hunt began shortly after.
Now, we've learned they pulled the trigger on a 5 bedroom, 6 bath East Coast country style home ... it's 5,000 square feet with an enormous pool and hot tub, koi ponds, park area to entertain gusts .