The 34-year-old Filipino veteran claimed the vacant WBO international welterweight title on Saturday after putting Rios down in the opening round and, while Pacquiao was unable to land a knockout blow, he did enough to notch the 55th win of his illustrious career.
The judges awarded the fight 120-108, 119-109 and 118-110 to Pacquiao as the Filipino tasted victory for the first time since 2011 after losses to Timothy Bradley and Juan Manuel Marquez last year.
Pacquiao landed 281 punches on his American opponent, while Rios got only 138 on target with the latter only having the better of the fight in the third round.
By the seventh round, Rios was cut under both eyes and, with Pacquiao going conservative in the final few rounds to ensure he did not cop a stray knockout blow - as he did versus Marquez, the fight petered out.
"Recovering from the knockout and giving a good show was what I wanted to prove to myself and everyone," Pacquiao said after the bout.
Pacquiao is expected to try and organise a rematch with Marquez.