Morton, whose contract was purchased from the Braves' Triple-A Richmond club earlier in the day, allowed three runs and five hits in six innings with four strikeouts and a walk.
The 24-year-old right-hander is the ninth pitcher to start a game for the Braves, who have John Smoltz, Tom Glavine and Mike Hampton on the disabled list.
A third-round pick in the 2002 draft, Morton threw 64 of his 104 pitches for strikes. He was 5-2 with a 2.05 ERA in his first season at Triple-A and didn't allow a home run in his 79 innings.
The Braves cleared a roster spot by placing closer Rafael Soriano back on the 15-day DL, retroactive to June 6. Soriano, who signed a two-year, $9 million contract in January, came off the DL on May 28 and made only five appearances after being sidelined for six weeks because of a sore right elbow.
Kelly Johnson also homered for the Braves, who won 5-2 Friday night and have recorded consecutive victories on a road trip for the first time since April 11-12 at Washington. They are a major league-worst 9-24 away from Turner Field.
Atlanta third baseman Chipper Jones was back in the lineup after a freak batting practice mishap that kept him out of Friday's game. He went 0-for-3, lowering his major league-leading average to .409. Jones also walked twice, once with the bases loaded against Justin Speier during the Braves' three-run eighth. Teixeira followed with a two-run single off Darren O'Day for a 9-3 lead.
Ervin Santana (8-3) gave up six runs, nine hits and two walks in 5 2-3 innings and struck out six. The right-hander came in with the fourth-best ERA in the AL (3.01), but it rose to 3.40 after his worst outing of the season. It was the second time in 14 starts that he failed to last at least six innings, and the first time he allowed two home runs.
Trailing 2-0, the Braves took the lead with four runs in the fifth. They loaded the bases with none out before Yunel Escobar followed Gregor Blanco's bunt hit with a two-run single. Santana walked Chipper Jones one out later, then hit Teixeira on the left foot to force in the go-ahead run. Brian McCann capped the rally with an RBI single.
Atlanta increased its margin to 5-2 in the sixth on solo homers by Brandon Jones and Johnson. Jones was playing in his third major league game after being promoted from Triple-A on Wednesday.
Morton struck out his first two batters, Chone Figgins and Maicer Izturis, and retired seven in a row before Gary Matthews Jr. sliced an opposite-field triple to left.
Matthews, batting eighth for the first time since Sept. 30, 2005, with Texas, was erased in a rundown as he broke for the plate on Mike Napoli's grounder to third. Morton walked Figgins, and Izturis double to left-center, scoring the first two runs.
The Angels got another run in the sixth on Torii Hunter's RBI double.
Notes: The Braves have a makeup game on Monday at Colorado, then it's on to Arlington, Texas, where Teixeira played his first 4 1/2 seasons before the Rangers traded him to Atlanta at last year's trading deadline. "I had a great time there and I'm really looking forward to going home and seeing some old friends," said Teixeira, who led the Rangers in homers and RBIs for three straight seasons.