The music mogul mentored Stevi on the last series of X Factor, which is where he met fellow singer Chloe-Jasmine, who was mentored by Cheryl Fernandez-Versini.
They became engaged this summer and are currently appearing in Celebrity Big Brother, where they are acting as one housemate.
Simon told Daily Star: "If I'm invited to the wedding, I'll go, yes. It's astonishing. I mean, these are the last two people I would have matched a year ago.
"Stevi is a very nice guy. I am so happy for him."
Ahead of entering CBB, the couple admitted they were gutted to be missing the new series of X Factor, which is currently airing on ITV.
"We are devastated, especially Steven, who absolutely idolises Simon Cowell," said Chloe.
"I think that is the worst part about going into the CBB house, that we will miss The X Factor. It's all on record though isn't it? We can catch up when we leave."