The Angels, who increased their AL West lead to five games over Texas, also had a big night off the field. Looking to bolster an inconsistent rotation, they acquired two-time All-Star Scott Kazmir from Tampa Bay for two minor leaguers and a player to be named.
Morales, who tied a career high for RBIs, put Los Angeles ahead with a three-run shot in the seventh. He also opened the scoring in the second with a solo homer against Brett Tomko.
Morales doubled in each of his next two at-bats and added his 29th home run against Brad Ziegler (1-4) to break Chili Davis' 1996 club record for the most homers in a season by a switch-hitter.
For good measure, Morales added an RBI single in the eighth against Santiago Casilla. The Angels' first baseman leads the AL with 42 RBIs since the All-Star break and has a team-high 91 in his first full big league campaign.
The four extra-base hits by Morales also tied a club mark. His sixth-inning double off Craig Breslow drove in a run, hitting the top of the 18-foot wall in right-center and bouncing back onto the field. The umpiring crew had to look at a replay to uphold the decision by first base ump Greg Gibson, after Angels manager Mike Scioscia contended it was a homer.
All seven runs in the seventh were unearned, the result of first baseman Daric Barton's fielding error on a broken-bat grounder by Bobby Abreu.
Jose Arredondo (2-3) pitched two innings of one-hit relief for the victory after inheriting a 6-1 deficit. It was the ninth time this season that the Angels won after trailing by four or more runs. In Thursday's series opener, they were held to three hits in a 2-0 loss to Trevor Cahill.
Brian Fuentes got two outs for his major league-leading 37th save in 42 attempts after Kevin Jepsen gave up an RBI single to Kurt Suzuki.
Angels rookie Trevor Bell lasted just 2 2-3 innings in his fourth big league start, giving up five runs and seven hits, including Scott Hairston's sixth homer of the season during Oakland's five-run third. The right-hander has a 10.80 ERA since Scioscia inserted him into the rotation on Aug. 12.
Bell isn't expected to make another start any time soon, now that the Angels landed Kazmir.
Tomko was handed a 6-1 lead. The 36-year-old right-hander allowed two runs and four hits over 5 2-3 innings and struck out five in his third start with Oakland.