The appearances were the band's first Augusta performances in two years.
Since singing at Kicks 99's Guitar Pull in 2008, they've recorded four straight No. 1 hits on the country charts and racked up industry awards.
The first concert at the Bell Auditorium was a chance for the community to honor the achievements of Lady Antebellum members Charles Kelley, Dave Haywood and Hillary Scott -- and for the band to give something back.
"I've got to say we owe so much to the community. It's always been so supportive of us," Haywood said during the show to benefit the Medical College of Georgia Hospital's Children's Medical Center.
"Wherever we go, we take Augusta, Georgia, with us," said Haywood, who, like Kelley, is a graduate of Lakeside High School.
Augusta Mayor Deke Copenhaver presented the band with keys to the city and said a downtown street was being ceremonially renamed Lady Antebellum Way for the day.
Scott is a Nashville, Tenn., native, but Copenhaver said the city has "adopted" her.
The planned Evans Town Center Park in Columbia County will feature a Lady Antebellum Pavilion, Columbia County Commission Chairman Ron Cross announced.
The band in turn surprised three teachers -- Sheila Hancock, Jim Tau and Stacy Branch -- from their alma mater with $1,000 gifts to their classrooms from OfficeMax.
"A lot of our friends here haven't got to see us perform and hear us live, so it's always kind of fun to reconnect with them, too, and show them what we're out here doing," Kelley said in a media briefing after the concert.
The support of their families and the community has been vital to their success, band members said.
"Sometimes you just need to chase a dream, so you never look back and say 'What if,' " Kelley said. "They definitely helped me do that."
The money from the midday show will specifically benefit the pediatric cancer and blood disorder clinic, said Rebecca Bruni, the philanthropy coordinator for Medical College of Georgia Hospital and Clinics.
"We can't even begin to understand their generosity," Bruni said of the band. "We understand how busy they are. To take time out of their day to help our kids is amazing."
A final tally of money raised wasn't completed Monday.
Scott said children's charities resonate with the group.
"That's reality, and that's what people face on a daily basis," Scott said. "No one is immune to being affected by that."
Lady Antebellum arrived onstage at Bell Auditorium with thunderous applause and performed three of their No. 1 hits -- Need You Now, American Honey and I Run to You -- during the short acoustic set.
Fans who packed the venue said it was refreshing to see the band donate all of the proceeds to charity.
"That's awesome. It just shows that they care about the community and want to give back," Carmen Hensley, 22, said before entering the building.
Lady Antebellum fan club member Amy Misenheimer drove two hours from Summerville, S.C., with her 6-year-old daughter, Ada, for the performance.
To their delight, they had front-row seats.
"They're really talented," Misenheimer said. "They're not out-of-the-box musicians."
Augusta residents Jeffrey and Laura Holder know the Haywood family from Trinity-on-the-Hill United Methodist Church and were happy to hear about the midday show after the band's Monday evening concert sold out James Brown Arena in seven minutes.
Lady Antebellum's quick rise to fame since forming in 2006 is pretty "incredible," Jeffrey Holder said.
"Lots of people try to do that, but here they are making it in the music industry," he said.