Pacquiao, who has a 57-6-2 record and won world titles in eight different weight classes in a 20-year career, is set to battle Bradley in Las Vegas on April 9 for the American's WBO welterweight championship.
"This is my last fight," Pacquiao, 37, told a Madison Square Garden news conference on Thursday. "After this I'm going to retire and hang up my gloves and focus on my other big responsibility in my daily life, to help the people."
Pacquiao is a congressman in the Philippines but is hoping to secure a Senate seat in the May 9 election back home.
But first comes a boxing rubber match.
Bradley, 32, controversially beat Pacquiao when they first met in 2012 but the southpaw gained revenge in a 2014 re-match, scoring a unanimous decision win to regain the WBO welterweight title.
The American, now working with trainer Teddy Atlas, knocked out Brandon Rios in the ninth round of his last bout.
"Teddy and I and the team are going go to the lab and I'll come out a smart, smart monster on April 9," said Bradley (33-1-1), who has credited Atlas with improving his ring skills.
Pacquiao told reporters he has recovered from surgery to repair a torn rotator cuff in his right shoulder that limited him in a loss to Floyd Mayweather last May and that on Wednesday he received an all-clear from his surgeon.
Looking slender in a business suit, Pacquiao snapped off a pair of sharp right jabs to illustrate that his daily basketball workouts and ocean swims had helped him heal.
Pacquiao, who insists he won two more rounds than Mayweather in their so-called "Fight of the Century," said TV coverage of his training would offset loss in campaign time back in the Philippines as he prepares for the Bradley bout.
"I'm campaigning to have a good fight," he said. "If I win this fight convincingly that will excite the people."
Pacquiao admits a rematch with Mayweather, who has already retired, was his first choice for a final fight.
And if Mayweather were to reconsider and offer Pacquiao a rematch?
"I'll ask the people of the Philippines," Pacquiao said.
Image: Manny Pacquiao
Photograph: Kevork Djansezian/Getty Images
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