In Time magazine, Cyrus, 58, wrote about Lil Nas X and the song.
"I was having coffee and Ron Perry from Columbia Records sent me 'Old Town Road,'" the country crooner remembered. "He said Lil Nas X wanted me to sing on it. But I told Columbia it was perfect. I couldn't do anything to it."
Perry eventually convinced Cyrus to collaborate with Lil Nas X, which was a seamless process.
"We wrote it with R&B songwriter Jozzy, and it was born right there in the studio. It was magical," Cyrus wrote. "I told Nas he was going to be a light in this world and he would shine brighter than anyone else. And he has. He's brought everyone together, from all musical genres and generations. 'Old Town Road' changed my world -- and his -- forever."
Cyrus' remix of the song hit the charts and the rest is history -- literally.
The record was previously held by Mariah Carey and Boyz II Men's "One Sweet Day" and Louis Fonsi and Daddy Yankee's "Despacito," which both spent 17 weeks at the top of the charts.
On Wednesday's episode of "Good Morning America," it was revealed that Lil Nas X and Cyrus will be awarded the Musical Event of the Year award for their collaboration.
"Old Town Road" also won Song of the Year at the MTV Music Video Awards in August.