Pacquiao entered the fight coming off successive defeats, having spent a year out of the ring and with his own trainer publicly declaring he should retire unless he convincingly beat Rios.
In addition, Pacquiao carried the burden of being the favourite son of the Philippines and the man the nation looked to as a source of joy and hope in the wake of deadly Typhoon Haiyan.
Thousands of fans watched the fight on screens set up in the plaza of Tacloban, the Philippine city hit worst by the Nov. 9 disaster that killed more than 5,000 people and left huge numbers of the population homeless.
If Pacquiao felt pressure, he didn't show it in the ring at The Venetian casino in Macau, putting on a vintage display of his trademark combinations to wear down a gallant Rios and take a unanimous decision, claiming the WBO international welterweight title.
The judges scored it 120-108, 119-109 and 118-110. The Associated Press scored it 119-109.
"This is not about my comeback," Pacquiao said in the ring. "My victory is a symbol of my people's comeback from a natural disaster and a national tragedy.
"My journey will continue. I said we will rise again, and that's what happened."
Pacquiao's points loss to Timothy Bradley last year was widely regarded as a judging error, but when that was followed by a severe knockout at the hands of veteran Juan Manuel Marquez, many doubted the Filipino lawmaker could get back to the kind of form that had made him the world's pound-for-pound champion.
Once again he failed to stop his opponent — he has not done so since 2009 — but everything else about Pacquiao's performance suggested he could revive his career, even with his 35th birthday looming next month.
Problems still exist in setting up a much-discussed bout with Floyd Mayweather Jr., but Pacquiao remains eager for it to happen.
"Anybody who wants to fight with me, I can fight," Pacquiao said. "I am willing to fight Floyd, but it's up to him, if he is willing also."
Pacquiao got the better of Rios over the first two rounds, sending the American to the canvas in the opening frame, although the referee ruled it as a slip rather than a knockdown.
Rios asserted himself in the third, landing some crisp blows that raised hopes of a genuine contest. But Pacquiao — spurred on by a capacity crowd at the 13,000-seat Cotai Arena dominated by Filipino fans — controlled the remainder of the contest.
Rios was game, absorbing plenty of punches and continually walking forward to challenge Pacquiao, but was unable to land any significant blows.
After seven rounds, Rios was getting attention to cuts under both eyebrows, and with the scores going against him, needed something special.
Pacquiao was on guard throughout the closing rounds, mindful of getting knocked out in his previous fight when he walked into a savage right by Juan Manuel Marquez. He didn't have to worry. A tiring Rios offered little threat.
"Recovering from the knockout and giving a good show was what I wanted to prove to myself and everyone," Pacquiao said. "I am so happy, my time is not over."
Rios trained for the bout with the quickest sparring partners his camp could find, but even that could not prepare him for the fusillade of Pacquiao punches from all angles.
"What got me was just the speed and his awkwardness," Rios said. "He never hurt me at all, and I never got stunned at all, but the quickness just caught me off guard."
Pacquiao's trainer, Freddie Roach, was frustrated by another fight without a knockout, but was enthusiastic about his fighter's performance.
"Manny looked great tonight," Roach said. "There were no signs of him slowing down whatsoever.
"Manny let him off the hook, I wanted the knockout and it was there, but I was very happy with the way he performed."
Promoter Bob Arum of Top Rank said the tentative date for Pacquiao's next fight is April 12, likely in the United States.
A rematch with Bradley or a fight against Russian Ruslan Provodnikov looms as more likely than a rematch with Marquez due to the Mexican's high asking price. Arum also holds out hope that the Mayweather fight could happen.
"I know it's a fight that should happen and where there is a will there is a way," Arum said, expressing his frustration that the fighters' conflicting affiliations continued to be an impediment. "If all sides cut out the crap, it can be done."
Rios, who has now lost his past two bouts after having previously being undefeated, had come up two weight classes in three fights, but said he would now stay at welterweight and perhaps even move up to super welterweight.