Blake Bortles -- along with 2 of his Jacksonville Jaguars teammates -- stopped an alleged thief from stealing the QB's truck from a Florida house party ... cops say.
It all went down late Wednesday night ... Blake and Jags lineman Chris Reed were all at a party at the Jacksonville Beach home of offensive lineman Brandon Linder when they noticed a strange young man skulking around the house.
Once the guys realized he wasn't an invited party guest ... they tracked him down inside the home, stopped him and called police.