"No person I'd rather spend the rest of my life with than you... My best mate... The one I can be my ultimate, weird, dramatic, emotional, true, honest self with," he added.
"I can truthfully say, I have found my soul mate... I love you my fiance... Mo ake tonu ake."
The model and TV personality shared a similar caption on her Instagram feed, announcing she had said yes.
The couple have been together for a number of years, albeit with a break in between.
News of the couple's engagement might not come as a surprise to eagle-eyed fans after Walker dropped a hint in a recent post on Instagram.
Alongside a photo of himself and Tyson, the singer wrote: "I'm gonna marry this woman".
