He took to social media on Sunday evening to address the incident.
“Some good advice... If you buy an electric trail bike, read the manual before you ride it for the first time,” the America’s Got Talent judge tweeted. “I have broken part of my back. Thank you to everyone for your kind messages.”
“And a massive thank you to all the nurses and doctors,” Cowell, 60, added. “Some of the nicest people I have ever met. Stay safe everyone. Simon.”
Some good advice... If you buy an electric trail bike, read the manual before you ride it for the first time. I have broken part of my back. Thank you to everyone for your kind messages.
"Simon had a fall from his bike testing his new electric bike in the courtyard at his house in Malibu with his family," Cowell's rep told ET. "He hurt his back and was taken to hospital. He's doing fine, he's under observation and is in the best possible hands."
Cowell’s son, Eric, and brother, Adam, were with him when he fell off his electric bike. During surgery he underwent a number of procedures and fusions, including having a metal rod inserted in his back.
ET has learned that doctors have said it's a bad injury, but Cowell is very lucky.
"Simon has broken his back in a number of places in a fall from his bike whilst testing a new electric bike in the courtyard of his home in Malibu with his family,” a rep for the British star told ET. “He was taken to hospital where they operated overnight (Saturday). He's under observation and is doing fine."
Cowell will not participate in Tuesday and Wednesday's live telecasts of America's Got Talent.
On Sunday, fellow AGT judges Heidi Klum and Sofia Vergara took to social media to wish him well.