The legendary pitcher -- owner of 1 career home run in his 21 MLB seasons -- showed he actually really does have pop in his bat ... cranking a softball roughly 400 feet in the D.R. on Sunday!!!

Check out the footage of the dinger filmed by MLB insider Hector Gomez ... 47-year-old Colon took a fastball DEEEEEEEEEP to center field before casually rounding the bases.

Of course, Bart was never known for his hitting prowess ... his lone home run in his career in 2016 is still one of the most fun moments in baseball history -- but it's clear the dude can rake if needed.

What isn't clear, though, is if Colon's homer helped his team win over the weekend ... according to Gomez, the game was nothing more than a pickup contest with some buds in his hometown.