When one door closes, another opens ... and that's exactly the case for Manny Pacquiao -- 'cause he tells TMZ Sports he's leaving his political career behind him for good ahead of his big boxing comeback.
The eight-division boxing champ served as a senator of the Philippines from 2016 to 2022 ... and followed up by running for the president spot, but lost by a wide margin.
Nearly four years after his last fight, the 46-year-old is making his return to boxing against Mario Barrios on July 19 in Las Vegas .