The Boyzone singer and 31-year-old Storm Uechtritz have been dating since 2012 - the year after he separated from his wife Yvonne, the mother of his three children.
Confirming the engagement news to Hello! magazine, Ronan Keating said happily: "I proposed twice and she said yes both times, thank God!”
The 38-year-old went on to explain how he got down on one knee the first time during a recent trip to Thailand.
However the couple decided to wait until they were back in Ireland, surrounded by his children, Jack, 16, Missy, 14 and nine-year-old Ali, before they would do an official proposal.
He said: “Storm isn’t just marrying me there are four of us involved.
“Storm has an amazing relationship with the kids, which is very important.”
Ronan added firmly: “We've been together a few years now and knew we wanted to spend the rest of our lives together. I felt it was the right time."
Speaking about her romance with the Rollercoaster singer, Storm said last year: "We've both found our soulmate and we know that we are going to spend the rest of our lives together. He's amazing; I love him."
She added: "We've talked about having a baby and it is a possibility for us, yes."
Their engagement announcement comes just one month after Ronan's divorce from Yvonne was finalised.
He wed the model in 1998 after a whirlwind romance, and they were married for 17 years.
Their marriage ended shortly after he embarked on an affair with dancer Francine Cornell. Yvonne initially gave her cheating husband a second chance but the couple split for good in 2011.
Congratulations to Ronan Keating and Storm Uechtritz!