The 29-year-old model and blogger from Tipperary was surprised by her fiance Gary at the Eiffel Tower in Paris this weekend.
She shared an image of the proposal as Gary dropped down on one knee beside the French landmark and another image of her stunning ring.
"Best day ever and I'm so excited to be marrying the love of my life. I'm engaged!!!" she wrote, adding, "Feeling like the luckiest girl in the world."
Following her Miss Ireland success in 2013 and ensuing modelling career in Ireland, Aoife moved to New York in early 2017, where her boyfriend already lived, and where she signed to a US agency.
She walked in New York fashion week last year and now divides her time between Ireland and New York.
Speaking to Independent.ie earlier this year she said that the modelling industry in New York is tough.
"I just think it's harder in New York because the industry is so much bigger. You'd be going on a casting with girls and you might hit it off, but you won't necessarily ever see them again," she said.
"I think it's easier in Ireland because the industry is smaller and everyone knows everyone.
"You see the same faces all the time, so you build a relationship. You just see them more often."