Barrett took to Instagram to share the happy news.
"She's a tough one to surprise but I got her good this time. Thankfully she said yes!" he wrote.
His new fiancee described it as the best day of her life and posted a photo proudly showing off the stunning pear shaped diamond ring.
"Yesterday, the best day of my life so far. Thank you for making me so happy, I feel like the luckiest girl alive" she gushed.
They had already been holidaying in Fiji for a few days with family when Barrett took Laity completely by surprise, whisking her away to Tokoriki Island Resort where he planned to propose, even packing her bag for the getaway.
Laity said she was "totally shook" by the gesture and joked that his choice of clothes for her was "interesting".
The pair have been together four years, and Laity playfully refers to them as Beaudannah.
"You really are the most remarkable human being and without a doubt the better half of Beaudannah" she posted in August on their four year anniversary.
It's been a whirlwind few months for the pair. Barrett spent November in the UK and France on the All Blacks end of year tour, where Laity joined him. They immediately jetted to Monaco for the World Rugby Awards where he scooped player of the year for the second year running.
They then jetted to Japan on All Blacks duties and then Vietnam for a holiday, returning to New Zealand for Christmas, spending it in Beauden's hometown of New Plymouth. Then Byron Bay in Sydney, the Gold Coast for new year and then Fiji.