Foreman knocked Santos down with a right hand in the final round, but by then the outcome had long since been decided. He won 117-109 on two ringside scorecards and 116-110 on the third.
The fight wasn't exactly an artistic triumph, with both fighters head butting each other and Foreman throwing Santos to the canvas in the second round. But Foreman controlled much of the action and landed both the harder and more effective punches.
The fight was on the undercard of the Manny Pacquiao-Miguel Cotto title fight at the MGM Grand arena.
Foreman, who remained unbeaten in 28 fights, emigrated from Israel to Brooklyn and began studying to become a rabbi three years ago. He gave up the edge in experience to Santos (32-4-1) but pressured the WBA champion most of the fight to pile up an edge on the scorecards.
Santos, from Puerto Rico, was defending the title for only the second time after winning it two years ago. He hadn't fought in 16 months, and the inactivity showed in a fight he fought only in spurts.
Both fighters complained about head butts, and the fight was briefly stopped in the seventh round after Foreman was cut by a clash of heads.
In the final fight before the main event, Julio Cesar Chavez Jr. remained unbeaten with a lackluster 10-round decision win over Troy Rowland.
Chavez, son of the former Mexican great of the same name, was fighting for the first time as a middleweight in a career that began six years ago at 130 pounds. Despite moving up in weight classes and having 42 fights, Chavez (41-0-1) has yet to be matched against any top fighters in any of the various divisions.
His latest fight was no different, despite its place on the Pacquiao-Cotto undercard. Rowland (25-3) had only seven knockouts in his career, fighting almost all of his fights in or around his hometown of Grand Rapids, Mich.
