The plane was heading from Atlanta to Phoenix over the weekend when the man started having a heart attack. Several passengers and crew tried to help him.
Tebow walked over to the unconscious man and his family, then led a group of passengers in prayer, according to passenger Richard Gotti.
Medical workers met the flight at the gate when it landed. The man survived.
Tebow used a car that had been waiting for him to transport the man's family to a nearby hospital.
Delta Air Lines confirmed that the incident occurred but said that because of privacy rules, it could not confirm Tebow's involvement.
ABC News contributed to this report.