Donaldson's bases-loaded single off Fernando Rodney in the ninth inning lifted the Braves over the Washington Nationals 4-3 on Friday night after Luke Jackson allowed a tying, two-run homer to Victor Robles in the top half.
Ronald Acuna Jr., who had three hits, led off the bottom of the ninth with a walk off Rodney (0-3) and took second on Dansby Swanson's single. Freddie Freeman walked on four pitches, loading the bases.
Nationals manager Dave Martinez brought in left fielder Juan Soto as a fifth infielder, including three on the left side against the right-handed hitting Donaldson.
Rodney's plan was "get a ground ball for a double play."
Instead, Donaldson lofted a 2-0 pitch over Robles to the warning track in left-center, and the Braves boosted their NL East lead to 6 1/2 games over the second-place Nationals. Atlanta had lost its previous five home games against Washington.
The Braves have six walk-off wins but it was Donaldson's first game-ending hit since 2015 with Toronto. That void had not escaped his attention.
"I was actually looking at that today," Donaldson said.
Donaldson's teammates surrounded him near first base for an on-field celebration.
Entering the game, Donaldson's 14 homers since June 11 were tied with Cody Bellinger for the most in the majors in that span.
Donaldson, who signed a one-year, $23 million contract with Atlanta as a free agent, is hitting .255 with 22 homers. His power stroke as a cleanup hitter has given Freeman protection in the lineup.
"This is what I expect of myself," Donaldson said. "I'm just glad to be put in a situation where I could help the team win the ballgame."
Martinez said Nationals closer Sean Doolittle was ready in the bullpen. Martinez said he liked the matchups with Rodney against Acuna and Swanson, even though the 42-year-old Rodney rarely is asked to pitch more than one inning.
"When you're playing on the road, Doolittle comes in the game for a save," Martinez said. "With a tie game, if he comes in right there and we have to pinch-hit for him right away, then we're looking at who knows who?"
Robles' homer went 446 feet to left, giving Jackson his seventh blown save in 24 chances.
Julio Teheran gave up one hit through five scoreless innings and retired 14 consecutive hitters before pinch-hitter Gerardo Parra singled with one out in the sixth. Anthony Rendon chased Teheran with a two-out RBI single.
Nationals: RHP Max Scherzer, on the 10-day IL since July 10 with an injury originally announced as a mid-back strain, was given a cortisone shot on Tuesday to address inflammation in the bursa sac under his right shoulder blade. Scherzer still has some discomfort and must throw a bullpen session before cleared to pitch in a game. With Scherzer unavailable, RHP Austin Voth is expected to start in Sunday night's series finale.
Braves: RHP Patrick Weigel, who had Tommy John surgery in 2017, was recalled from Triple-A Gwinnett for his major league debut. Weigel will pitch in relief. ... RHP Wes Parsons also was recalled from Gwinnett. RHPs Kyle Wright and Touki Toussaint were optioned to Gwinnett.
Corbin couldn't win on his 30th birthday while paired with catcher Yan Gomes, who turned 32. Corbin and Gomes became only the second pitcher-catcher tandem to start together on their birthdays since 1900, according to the Elias Sports Bureau. Chicago Cubs pitcher Dave Hillman and catcher Jim Fanning did it against Pittsburgh on Sept. 14, 1957.
Freeman was 2 for 20 in his career against Corbin before his RBI single in the fifth.
Acuna has reached base in a career-best 26 consecutive games since June 19, the longest active streak in the majors. Donaldson's on-base streak was extended to 16 games.
Nationals: RHP Anibal Sanchez (5-6, 3.71) is 1-0 with a 3.00 ERA in two starts this season against the Braves, his former team.
Braves: Rookie RHP Mike Soroka (10-1, 2.24) will try to win his sixth straight decision on Saturday night. The 21-year-old right-hander became the youngest pitcher in franchise history to be selected an All-Star.
More AP MLB: https://apnews.com/MLB and https://twitter.com/AP-Sports
Lefty Al Jackson, an original Met, dies at 83
Al Jackson, a tough left-hander who provided a rare glint of hope in the early days of the woebegone New York Mets, has died at 83.
Sources: Boston's Sale likely avoids Tommy John
Red Sox left-hander Chris Sale will likely avoid Tommy John surgery, sources told ESPN's Jeff Passan.
Dark cloud looms over Red Sox ahead of series vs. Phillies
The Boston Red Sox are riding the high of a five-game winning streak, but a dark cloud still looms over the team in the form of the mystery surrounding ace left-hander Chris Sale's throwing elbow.
Jubilant Cubs aim for strong showing against Giants
The Chicago Cubs figure to be in a good mood when they open a six-game homestand starting Tuesday night against the San Francisco Giants.
German goes for 8th straight W as Yanks visit A's
The Oakland Athletics get a rematch with the team that ended their season a year ago when they open a three-game series against the visiting New York Yankees on Tuesday night.
Fantasy baseball daily notes: Pitcher and hitter rankings for Tuesday
Prepare your fantasy baseball lineups confidently with our daily preview, including pitcher projections, hitter matchup ratings and more.