The Derry-born singer revealed that her partner of two years popped the question while she was in her pyjamas.
And the unconventional proposal involved him going down on two knees rather than one after he hurt himself while playing.
“It was really, really nice,” she said.
Coyle let slip with her news after being quizzed by Radio 1 DJ Scott Mills about the sparkly ring she was wearing when she appeared on his show.
She said they became engaged last week when they were in Los Angeles.
“I had just got back from London, and he was in New York and then he surprised me with a ring and stuff, while I was in my pyjamas.
“If I’d have known I would have got a blow dry, or at least got a manicure or something – but no,” she said.
She added: “It was different.”
Previous boyfriends of the star have included Desperate Housewives actor Jesse Metcalfe.