Justin Bieber has vowed to "always" put Hailey Baldwin first after gushing about the model as he declared his new fiancee the love of his life.

The Sorry hitmaker hit headlines over the weekend after apparently proposing to Hailey on Saturday, while on vacation in the Bahamas, and on Monday, he took to Instagram to confirm the news and pledge his undying love to his future bride in a lengthy caption.

"Was gonna wait a while to say anything but word travels fast," the pop superstar began, alongside a pair of black-and-white snaps of the smiling couple.

Addressing his fiancee directly, he wrote, "listen plain and simple Hailey I am soooo in love with everything about you! So committed to spending my life getting to know every single part of you loving you patiently and kindLY (sic)."

"I promise to lead our family with honor and integrity letting Jesus through his Holy Spirit guide us in everything we do and every decision we make," Justin continued. "My heart is COMPLETELY and FULLY YOURS and I will ALWAYS put you first! You are the love of my life Hailey Baldwin and I wouldn't want to spend it with anybody else."

"You make me so much better and we compliment eachother (sic) so well!!," he exclaimed. "Can't wait for the best season of life yet!. It's funny because now with you everything seems to make sense…!"

The singer, 24, went on to marvel at "Gods timing (sic)", and concluded his message by sharing his excitement at spending the rest of their lives together: "My goodness does feel good to have our future secured!" Justin shared. "WERE (sic) GONNA (be) BETTER AT 70 BABY HERE WE GO (sic)…!"

Hailey, 21, also broke her silence over the engagement news in a Twitter post on Monday, a day after showing off her huge oval diamond ring while hitting the beach.

"Not sure what I did in life to deserve such happiness but I am so utterly grateful to God for giving me such an incredible person to share my life with!" she wrote. "No words could ever express my gratitude."

The young stars previously dated in early 2016, but rekindled their romance in June, three months after Justin split from on/off girlfriend Selena Gomez.

They have since been enjoying the summer with trips to Florida and New York, before jetting off to the Bahamas.