The pair fell out when the Promise This hitmaker was axed from the US version of the talent competition.
But the pair are said to have made amends after 51-year-old Cowell sent Cole, 28, a text message saying: 'Friends again? X.'
According to British newspaper the Daily Mirror, Cole's response was: 'You've got a nerve!… X.'
The Geordie singer has reportedly moved on from the incident and Cowell is 'delighted' to have his friend back.?
A source told the publication: 'Cheryl was thoroughly hurt and embarrassed by the whole US debacle. But she's done a lot of thinking over the past few weeks, and has moved on. She texted Simon back with a message poking fun at his treatment of her. Simon was delighted.'