The five scoreless innings were just a bonus.
Beckett struck out seven and allowed only four singles, helping Boston beat the Texas Rangers 8-1 on Friday night.
"When he left the game, he didn't feel anything," manager Terry Francona said. "He just pitched. There was nothing to report, which was good."
Pitching for the first time since Aug. 17 due to an inflamed right elbow, Beckett (12-9) struck out four of the first eight batters he faced. The right-hander, on a limited pitch count, threw 49 of his 80 pitches for strikes without walking a batter.
"I came out of the game healthy. That's what we were looking for," Beckett said. "I thought about it before the game more than anything. It's one of those deals, you've got to go out and push through it."
Mike Lowell also came off the disabled list, hit a home run in his first at-bat since Aug. 12 to put Boston ahead to stay, and finished 3-for-5 with four RBIs.
The Red Sox won their fourth straight game to move within 2 1/2 games of AL East-leading Tampa Bay, a 6-4 loser at Toronto. They remained 5 1/2 games ahead of Minnesota in the wild-card race.
All of that was secondary to Beckett's encouraging outing.
"It's definitely a nice stepping stone and easier to go out the next start and not worry about it," Beckett said.
"We were thrilled," Francona said. "He went out and commanded really well."
Kevin Millwood (9-8) allowed seven runs, six earned, and nine hits in six innings. The right-hander had won three straight decisions, his longest winning streak since 2002, giving up only four runs over 24 2/3 innings with two complete games in that stretch.
Lowell, who was on the DL with a strained right oblique muscle, put the Red Sox up 1-0 with his 15th homer in the second. The third baseman added a two-run single in the fourth and an RBI double in the ninth.
"It definitely gives me a boost," Lowell said. "I think you're curious. I didn't really think I would be totally lost, but there's a certain amount of uncertainty just because you haven't seen live pitching in three weeks."
Coco Crisp went 3-for-5 with three RBIs for Boston.
The Red Sox declared Beckett ready to return after he threw 58 pitches without any problems in a bullpen session Tuesday.
Beckett didn't allow a hit until Joaquin Arias led off the fourth with an infield single, the first of three Texas hits in the inning. But Michael Young grounded into a double play before consecutive singles and a strikeout.
Seven different Texas batters struck out against Beckett, who in his last start allowed a season-high eight runs in only 2 1/3 innings.
"He was probably easing himself in as far as velocity is concerned," Young said. "He was locating all his pitches, commanding his sinker well, mixing some curves, threw his breaking ball for strikes."
Crisp had a two-run single in the fourth, on a flare to short center that ricocheted off the glove of backpedaling second baseman Arias. The Red Sox had back-to-back triples in the sixth, Crisp driving in a run with his before scoring on Jacoby Ellsbury's triple into the right-field corner.
AL batting leader Dustin Pedroia extended his hitting streak to nine games with a double in the first, a play on which Texas left fielder Marlon Byrd sprained his left thumb trying to make a diving catch. Pedroia was 1-for-4 with a walk, dropping his average a point to .332.
Pedroia's liner short-hopped into Byrd's glove, which came off his hand when it hit the ground. Byrd stayed in the game then, but was replaced in the top of the second. X-rays were negative and the Rangers said Byrd is day to day.
The crowd of 30,264 was heavy with Boston fans, who were chanting "Let's Go Red Sox!" early in the game and easily drowned out the home fans.
"If we'd done some things, we could have shut those people up," manager Ron Washington said. "But they got the lead and they held on to it, so you heard more of the Boston crowd."
Boston is 8-0 against the Rangers this season, outscoring them 75-36. ... Crisp is 21-for-46 his last 13 games. ... RHP Tim Wakefield is scheduled to make his 500th career appearance for Boston when he starts Saturday night. Bob Stanley (1977-89) is the only Boston pitcher with more appearances (637).