Cubs' Kris Bryant Marries High School Sweetheart ... In Vegas, Baby! (PHOTOS)

Chicago Cubs superstar Kris Bryant is already killing in 2017 ... dude just married his high school sweetheart in a massive Vegas wedding -- packed with teammates and other MLB superstars.

The 25-year-old 3rd baseman swapped "I Dos" with Jessica Delp -- his girlfriend since high school -- at the J.W. Marriott in Sin City.

Some of the guests included Cubs' teammates Anthony Rizzo, Jason Heyward, John Lackey and Justin Grimm. Bryce Harper -- who also grew up in Vegas -- was there, too.

Bryant and Delp got engaged in 2015, he won the World Series and NL MVP in 2016 and is now married in 2017.

Dude's havin' a helluva run!