Filipinos from street vendors to lawmakers went wild, pumping their fists in the air during the first round of the welterweight fight as Pacquiao floored the WBA champion 10 years his junior, and went on to win by split decision, AFP reported.
Despite Thurman's threat to send Pacquiao into retirement in the Las Vegas showdown, fans of the eight-division world champion were thrilled to see him eat his words as they packed into gyms, military camps and movie theatres all over the country to watch the fight.
"It was wow, wow, wow! He is amazing. He showed himself a true Filipino, a hero," 51-year-old Raquel Sanders told AFP after watching the bout in a Manila sports complex.
The excitement also lit up the online world with fans in the social media-obsessed nation using the hashtag #StillA40rce.
"Senator Pacquiao proved that age is just a number and (he) still can make another legend," said Twitter user @rinrin_irene.
However, tragedy dampened the mood in Manila's Marikina suburb where a 68-year-old fan collapsed as he was watching the bout in a gym. He was rushed to the hospital but declared dead on arrival, police said.
The man had a heart illness and could have gotten "excited" and "overjoyed" upon watching Thurman getting knocked down, Marikina police said, but added doctors had yet to issue a medical report.
Pacquiao is considered a national hero by many as his athletic feats have put the Philippines on the boxing map.
His rags-to-riches rise from high school dropout to millionaire champion is a source of inspiration in a nation mired in poverty.
In Pacquiao's heyday, authorities said his fights stopped traffic and crime.
President Rodrigo Duterte's spokesman hailed his ally's victory.
"Our pound-for-pound King did not show any signs of intimidation as he embodied what a Filipino spirit is all about – a fighter," Salvador Panelo said in a statement.
Some Pacquiao fans said while their idol had proven his mettle, he showed signs of aging.
"He can still fight but not a long bout because he gets tired. A younger fighter would have more endurance than an older fighter," said Willieboy Ramos, 50.
Pacquiao, who reversed a 2016 decision to retire, repeatedly says boxing is his passion and he still feels young.
Philippine boxing chief Ed Picson said only Pacquiao could decide on his future.
"His place in world boxing as a legend is secure ... He has nothing more to prove," said Picson, secretary general of the Association of Boxing Alliances in the Philippines.
Pacquiao, who improved to 62-7-2 with 39 knockouts, was gracious in victory.
"I'm not that kind of boxer who talks a lot; we were just promoting the fight," he said.
"He's a good boxer and he's strong. I was just blessed tonight."
Pacquiao, who earned an estimated $20 million from Saturday's fight, is now a major player in the competitive welterweight division once again after capturing Thurman's WBA welterweight 'super' champion belt.
"I think I will fight next year," he said.
"I will go back to the Philippines and work and then make a decision."
Thurman meanwhile had few complaints in defeat, embracing Pacquiao after the final bell in recognition of an epic contest.
"I knew it was too close," Thurman said.
"He got the knockdown so he had momentum in round one.
"This was a beautiful night of boxing. I wish I had a little bit more output to go toe to toe. I felt like he was getting a little bit tired, but he did have experience in the ring. I would love the rematch."