Gaga's fans, accustomed to the grandiose Gaga -- she of the meat dress and egg-like containment vessel -- began camping out in New York's Central Park as early as 3:00 a.m. Tuesday, three days before the concert.
By Friday morning, thousands of "little monsters," decked in Gaga garb -- from outrageous hair pieces and blonde and bubble gum pink wigs to fishnets, sky high heels, glitter and more - filled the park.
The turnout made today's concert the biggest ever for a "GMA Summer Concert Series" event.
"I love my fans," Gaga told Roberts and Stephanopoulos. "They're my family, for sure. It's an absolute dream to play here in Central Park. And just to see this many people here to listen to my music makes me feel so blessed."
The dramatic staircase, steam machines and unicorn statue piano on the outdoor stage gave Gaga's excited fans an early hint of the show spectacular that was to come.
The singer whipped the crowd into a frenzy before the show even started, appearing onstage for a sound check. She wore her hair in a long blonde and black side pony tail, but that was just a preview of what she had in store for her followers.
"Fans are a part of the story that no one teaches you," Gaga said on "GMA." "I want to be a voice with them, among them."
Music, Family and Fans
For her first-ever live "GMA" performance, Lady Gaga focused on what her fans really wanted: her music. She delivered a high-octane set of five fan favorites, both old and new, with each performance leaving the crowd singing, dancing and wondering what would come next.
After opening with "Bad Romance," Gaga performed songs from her new album, including "Hair," "Judas, and "Edge of Glory," a song she told "GMA" she wrote for her grandfather, who died last September.
That sense of family -- both her birth family and her fans -- is a theme that weaves throughout Gaga's career, and continued at the concert today.
The singer, born Stefani Joanne Angelina Germanotta, told Roberts and Stephanopoulos she grew up in New York City, just five blocks from Central Park and the concert's stage, and that her parents were in attendance for today's concert.
In response to a "GMA" viewer question asking what she keeps with her at all times, Gaga quickly pulled out a necklace with her Aunt Joanne's miniaturized birth certificate attached, and pointed to a ring from her grandfather that she said she wears everyday.
And responding to another viewer question on what she would do if she ever had a day off, Gaga made it clear how closely she regards her fans.
"I would like to hang out with my fans and have it not be me," she said. "I'd just be one of them."
She also said she performs for the love of the music, not for fame or glory.
"I would still be a singer. I just wouldn't be famous," she said when asked what she would do if she weren't "Lady Gaga." "I don't do it for the money. That'd be miserable if I just gave up because noone bought my music."
Fashion Does Not Disappoint
Neither Gaga's flying entrance, nor the constraints of a harness and an outdoor performance, could prevent Gaga from showing off her trademark outrageous fashion.
She flew in on the zip-line wearing a white and red turban-like headpiece with a white cape.
Once on stage, Gaga's dancers removed her cape to reveal the singer in red fishnet stockings with black felt pieces, a red leotard, black lace-up booties with glitter and long black nails.
Each song brought a new costume, and new persona, for the pop icon.
To sing "Edge of Glory," the song written for her grandfather, Gaga began with an all black ensemble, a black masquerade mask and black lace veil. She shed the veil to reveal a pattern leather jacket with signature shoulder spikes.
For her performance of "Judas," the title track of "Born This Way," Gaga topped off her black sheer look with a gold bejeweled jacket, and gold-studded bikini top and bottom, while machines filled the stage with steam and fans belted out the chorus, "I'm in love with Juda-as, Juda-as."
For the No. 1 single and pop anthem "Born This Way," Gaga wore gold horns and a gold sequined jacket and joined her dancers in a vat filled with 1,800 pounds of hear gel dyed to create the effect.
But it was the show's grand finale, an acoustic, heartfelt rendering of "Hair," that really brought the house down.
Dedicating the song to her mother, Gaga wore a purple horn and a Gagaesque-blonde and black ponytail and sat atop a black lacquer staircase to play a black unicorn piano, with her leg perched on top.
Pulling out an array of different wigs, Gaga said, "Without my wigs, I feel like I can only be one person, and I want to be so many."
ABC News' Sheila Marikar contributed to this report.