Katy Perry stunned a survivor of the Orlando, Florida nightclub massacre by surprising him with a TV appearance.

Tony Marrero, who was partying at the Pulse nightclub in June (16) when a gunman opened fire, painfully recreated the moment he realised his life and those of his friends were at risk in a video he shot for The Ellen DeGeneres Show.

He said, "It was horrible. (There were) people screaming and crying, people saying their goodbyes."

The TV host, who admitted she "sobbed for 15 hours" after learning about the events at the gay club, invited Marrero onto her show and then surprised him by introducing him to Perry, whose 2016 song Rise helped him as he recovered from his injuries.

Tony was shot in the back four times and 'died' on his way to hospital. He was later revived. His best friend Luis was killed.

Ellen asked Marrero if he had ever met Katy and when she stepped out into the studio, all three began to cry.

"We're both electrified by each other and so inspired," Perry said after hugging her fan.

She then fought back tears as Marrero thanked her for her "powerful" music and told her how important Rise was to him as he recovered from his injuries in hospital.

"I'm happy to be a joy. I'm happy to be a light, and I'm happy I could be there in my own little way to help you," Perry said.

And there was one more surprise for the survivor - the singer offered to pay for his first year of film school.

Gunman Omar Mateen opened fire inside the Pulse nightclub on 12 June (16), killing 49 people and injuring more than 50.