Chris Johnson had three hits, including a two-run homer that capped a five-run first inning against Vance Worley, a drive just fair down the left-field line.
After the Pirates tied the score, Jonny Gomes hit a go-ahead home run in the ninth against Clayton Richard and Jesus Flores had a run-scoring infield single.
Rodriguez allowed four runs and eight hits in five innings. Worley retired 13 in a row after Johnson's homer and wound up giving up seven hits in six innings
Walker doubled and scored on Andrew McCutchen's single in the third inning, then homered in the fifth. Francisco Cervelli hit an RBI double.
At spring training with a minor league contract, the 36-year-old Rodriguez appears to have earned a spot in Atlanta's starting rotation. He gave up a run in his first inning this year against the New York Mets, then blanked Washington (three innings), Houston (four innings) and Miami (five innings).
''We have some familiarity with him,'' Harrison said. ''He was with us for a couple of years and before that we faced him a lot.''
Braves: Rodriguez went 0-2 with a 6.75 ERA in six starts last season before he was released by the Pirates. He had surgery on his right knee in July, then signed a minor league contract with the Braves in January. ''I left my fastball up a little bit, but everything was good,'' Rodriguez said. ''I feel if I put the ball where I want, I can get these guys out. But today, the ball was a little bit up in the zone.''
Pirates: Worley almost certainly has won the lone open rotation job. He was not surprised by his rough first inning against the Braves. ''My last outing against them last season, the same thing happened,'' Worley said. ''Their approach is a little bit different from everybody else's. They can handle the inside pitch a little bit better than other clubs. Once I made an adjustment, I was able to get the command I needed.''
Braves: C Christian Bethancourt was back in the lineup after missing a week due to flu-like symptoms. He went 1 for 3 and is batting .357. Bethancourt, 23, will handle most of the catching this season.
Pirates: C Chris Stewart (hamstring) is taking batting practice, but his status for opening day remains uncertain. Stewart began last season on the disabled list after minor knee surgery during spring training.
Braves: C John Buck, who was in camp as a non-roster player, announced his retirement. In 25 at-bats, he batted .320 with one home run. Buck, 34, is an 11-year veteran who played for Kansas City (2004-09), Toronto (2010), Miami (2011-12), the New York Mets (2013), Pittsburgh (2013), Seattle (2014) and Los Angeles Angels (2014).
Pirates: Andrew McCutchen turned up without his signature dreadlocks, which were cut off Wednesday. The locks will be auctioned, and the proceeds will go to Pirates Charities. ''I know I'm going to feel a little faster without all that hair,'' McCutchen joked. ''Now I can be like all the rest of the guys on the team and get a haircut every two weeks.''
Braves: Probable opening day starter RHP Julio Teheran will pitch Friday against the Boston Red Sox. Over three outings, Teheran has a 7.56 ERA and has allowed 13 hits in 8 1-3 innings.
Pirates: LHP Jeff Locke will start Friday against Minnesota. It will be his first outing in 10 days. Locke is out of minor league options, but is not expected to win the final spot in the starting rotation. If he's not traded, Locke likely would begin the season as a long reliever.