Ed Sheeran debuts new song at New York City gig - video
The singer-songwriter told the audience that he had written the track for a "friend of a friend" who was diagnosed with cancer and given just four months to live.
However, Sheeran assured his fans that two years later the cancer victim was still alive, despite the doctor's prediction.
The musician also explained that he hopes the new track will feature on his second studio album.
The new collection will serve as the follow-up to his multi-million-selling debut +, which topped the UK chart and reached number five on the US Billboard 200.
Sheeran recently told Digital Spy that he aims to make his second studio record more "mature".