Paul, whose last fight was a controversial clash with 58-year-old former heavyweight champion Mike Tyson in November, dominated from the outset to win by unanimous decision.
The 28-year-old influencer, who has earned millions from a string of lucrative contests in a ring career that has spanned 13 fights, had too much speed and power for Chavez Jr.
The three judges at ringside scored the 10-round fight 99-91, 97-93, 98-92 in Paul's favour.
Chavez Jr, the 39-year-old son of Mexican boxing great Julio Cesar Chavez, barely looked capable of mustering a response during a one-sided bout.
Chavez Jr failed to land a single punch in the opening round, a pattern that followed the remainder of the contest, with Paul easily outscoring the veteran of 63 professional fights.
Paul, who reportedly pocketed around $40 million for his made-for-Netflix fight with Tyson last year, received around $300,000 guaranteed from Saturday's bout.
However the American is expected to earn around $8-10 million from the fight once earnings from pay-per-view and sponsorships are taken into account.