The singer, who revealed that he was dating the former V star in 2005, confirmed the news on his Twitter page.
"Sadly, Kevin & I are no longer together," Feehily wrote. "We've had an amazin 7yrs &are both so thankful for the love&support u have shown us from the start."
He added: "We won't be answering any questions about this as its a very private matter.Thanks in advance for understanding that.Lots of love,Mx"
The couple announced their engagement in February 2010, after Feehily proposed to McDaid while they celebrated their fifth anniversary in Ireland.
Last month, the 31-year-old said that they would "definitely" marry in 2012, once Westlife had completed their farewell tour.
"We want to do it as soon as we possibly can, but we want it to be right as well. It's finding the time and doing it right. We've no reason to rush it or say, 'Let's just f**king pick any church or hotel or venue in the country'," he said at the time.
Westlife will go their separate ways after completing their farewell tour across the UK and Ireland next summer.
Watch Westlife's video for new single 'Beautiful World' below: