Beltre hit his 19th home run in 25 games and did so one night after he had been held out due to a stomach virus.
Texas defeated the Angels for the second straight night and maintained a four-game lead over Oakland in the American League West with both teams having 13 contests remaining. The Athletics and Rangers will meet seven times over the final 10 days of the season.
Yu Darvish of the Rangers and Matt Greinke of the Angels staged a battle through eight innings, but Texas quickly struck against Ernesto Frieri (4-2) in the ninth.
Michael Young singled on the second pitch of the inning and Beltre, who told Manager Ron Washington before the game that he felt strong enough to play, launched a long home run to left on a 2-1 pitch.
Greinke struck out eight and gave up five hits and a run before giving way to Frieri.