In an 11-3 win over Colorado, Cunningham pinch-hit for pitcher Alex Wood in the seventh inning and got a hit in his major league debut. He scored when Freddie Freeman followed with his second homer of the night.
Cunningham remained in the game and played left field in the eighth and ninth innings, replacing Evan Gattis.
Cunningham was called up from Triple-A Gwinnett on Monday night when outfielder Reed Johnson was placed on the 15-day disabled list by the Braves.
Cunningham, a second-round draft choice in 2010, had a .279 batting average with 30 RBIs and 18 stolen bases for Gwinnett in 99 games this season. He was the Braves' organization player of the year in 2012 after hitting .309 at Double-A Mississippi.
A Jacksonville High graduate, Cunningham played for the Gamecocks during 2008-10 before joining the Braves' organization. He was a Baseball America first-team All-America selection in 2010 when he helped JSU to the Ohio Valley Conference title.
Cunningham told the Atlanta Journal-Constitution he was surprised by the call to come to Atlanta.
“(Cody) Rasmus had just been traded yesterday,” Cunningham said. “So I got the call at about midnight and my first thought was, ‘Where am I going now?’ like I was involved in some kind of trade. So it was a pleasant surprise to find out I was coming to Atlanta, as opposed to some other ball club.”
The win was Atlanta's fifth straight. The Braves trailed 3-1 before scoring 10 unanswered runs and moved 10 games ahead of second-place Washington on the NL East. They lead the majors with a 36-15 home record.
Freeman had four RBIs with his first multihomer game this season and fourth of his career.
Wood (1-2) earned his first career victory after allowing six hits, three runs, one walk while striking out seven in seven innings.
Juan Nicasio (6-5) allowed 10 hits, a season-high eight runs, three walks and struck out four in four innings. Colorado has lost 16 of 19 series games against Atlanta.
The Rockies led 1-0 in the first on Carlos Gonzalez's sacrifice fly and went ahead 3-1 in the second on Nolan Arenado's ninth homer, but Nicasio couldn't hold the leads.
Since getting recalled July 12 from Triple-A Colorado Springs, Nicasio had gone 2-0 with a 0.47 ERA in three starts, but the right-hander was finished after making 31 pitches in the fourth.
Nicasio dropped to 0-3 and has a 9.82 ERA in four career starts against Atlanta.
Freeman's 13th homer, a three-run shot off Edgmer Escalona, put the Braves up 11-3. In 67 games since May 15, Freeman is hitting .311 with 11 homers and 50 RBIs.
Colorado's Michael Cuddyer singled in the seventh and tried to score from first on Wilin Rosario's double, but was tagged out at the plate.
Heyward overran the ball in left-center and had to turn back two steps to pick it up, but his relay to Andrelton Simmons was on time, and Cuddyer was cut down on McCann's tag.