Buttigieg read Zachary Ro's question out loud and then invited the 9-year-old to join him on stage as the crowd cheered and chanted "love is love."
"Would you help me telling the world that I'm gay too? I want to be brave like you," the question read.
Buttigieg, the first openly gay candidate to earn presidential primary delegates, commended Ro on his own bravery and told him he struggled with coming out.
"It took me a long time to tell even my best friend that I was gay, let alone to go out there and tell the world, and to see you willing to come to terms with who you are in a room full of a thousand people, thousands of people you've never met, that's really something," the South Bend mayor said.
Buttigieg then told Zachary he should always be true to himself and said his own bravery could inspire others.
"When you know who you are, you have a center of gravity that can hold you together when all kinds of chaos is happening around you," he said.
Zachary also gave Buttigieg a handmade bracelet.
After the event, Zachary told KDVR-TV he appreciated Mayor Pete's advice.
"I just feel inspired by Pete being openly gay and running for president at the same time and someday, I want to be like him," he said.
Zachary's dad also said he's very proud of his son.