The former NL MVP has been sidelined the entire season after rupturing his left Achilles tendon while making the final out in Philadelphia's loss to St. Louis in Game 5 of the NL division series last October. He's missed 84 games.
"It feels good. I'm ready to go and get back in the swing of things," Howard said.
Howard played in seven minor league games and went 10 for 20 with a home run. He'll be back at first place for the first time when the last-place Phillies open a three-game set against Atlanta.
"We think he's ready to play and we want him in the lineup," manager Charlie Manuel said. "We think he can handle it."
Howard was hoping to return by May before suffering a setback during spring training. He developed an infection around his Achilles that required a surgical procedure, forcing him to slow down his rehab.
The five-time defending NL East champion Phillies entered the night at 37-47 and 13 games behind division-leading Washington. They just got Chase Utley back last week, but have gone 1-7 since the five-time All-Star returned to the lineup.
With Utley and Howard hitting 3-4 for the first time, Manuel is looking for his team to make a run.
"We need to play better than the first half," he said. "Getting those two guys back will create more offense. Hopefully we can go back to the resilient team we used to be. We don't ever quit."
Howard, the 2006 NL MVP and three-time All-Star, averaged 44 homers and 133 RBIs per season between 2006-11.
"Watching him hit, he's using his back side pretty good," Manuel said.
Howard never was a speed demon, and he's clearly a slower runner now. Manuel said he'll run for Howard and take him out for a defensive replacement when the situation dictates it. Howard isn't expected to start on Saturday, but should be back in the lineup on Sunday, Manuel said.
Infielder Hector Luna was sent to Triple-A Lehigh Valley to make room for Howard. Luna hit .246 with two homers and 10 RBIs in 26 games.