Luke Combs wrote the track with Sammy Mitchell, Steven Andre Battey, Carlos Battey and Robert Williford. He recalled the story of the song during an interview with The Boot
"Steven is an LA guy. I had just moved to town, and Rob introduced me to the other writers and suggested I come in and sing some demos for them. So I did, and we decided to sit down and try writing something. The second time we wrote, we got 'One Number Away.' Rob had the idea written down in his phone - I can't tell you where he got the idea.
Steven is an incredible melody guy, so he said that he had this melody in his head that he really liked, and started humming the chorus of it. We just sat with it for a while. So Steven had the chorus, and then Sandy wrote the track. I had never written with a track guy before; I didn't know that was a thing."