Packer proposed to Carey, who filed for divorce from America's Got Talent host Nick Cannon in December 2014, in her hometown Thursday night, E! News reported.
The singer and former American Idol judge's beautiful diamond ring is reportedly 35 carats, and according to an insider, they both "couldn't be happier" and are "perfect" together.
Although Carey and Packer have been friends since meeting at a 2014 movie premiere in Aspen, they began dating just about a year ago and have enjoyed a whirlwind romance ever since.
"They fell head over heels in love with one another, " the insider told E! news. "They are just very cute together, they like doing sweet things for one another. They want to make each other happy."
No wedding date has been set, but it's probably tough to nail one down considering the pair's hectic schedules. Carey is finishing up her Las Vegas residency at Caesars Palace before jetting out on a world tour, and while Packer will join her for many of the tour dates, he's also involved with philanthropy work.
"As soon as their friendship turned romantic, they have wanted to spend every moment together," a source told the website. "They have a connection that is unparalleled; it's been a very beautiful experience for them both. If you spend even five minutes with them, you can't help but believe in true love."
Carey and Packer have traveled the world together in their 10 months as an item. The couple visited Ibiza, Saint Bart's, Italy, Australia, and Israel. In Israel, the pair reportedly shared a very intimate and "spiritual" moment together at the Western Wall.
"[Packer] is aware Carey has the world at her fingertips but he likes to find things that she has never experienced," another source told E! News.
This will be the third marriage for both Packer and Carey.
Carey's first marriage was to music producer Tommy Mottola, and then she wed Cannon in April 2008. The singing diva and Cannon welcomed twins Monroe and Morrocan in April 2011, but the pair ultimately filed for divorce in late 2014 after several months of separation.
Packer has three children of his own -- Indigo Packer, 7, Jackson Packer, 5 and Emmanuelle Packer, 3.