Reese began dating the Hollywood agent in January and there had been rumours Jim was planning to propose after he was spotted looking at engagement rings earlier this month.
It has now been confirmed Reese has agreed to marry Jim and the couple are looking forward to spending their lives together.
“They are extremely happy,” a representative for the actress told Us Weekly.
Reese fell for Jim shortly after she split from Hollywood heartthrob Jake Gyllenhaal and they went public with their relationship in March as they celebrated Reese’s birthday together.
Those close to the 34-year-old believe she has finally found true love and have revealed Jim has formed a close bond with 11-year-old Ava and Deacon, seven – Reese’s children with her ex-husband Ryan Phillippe.
“She is definitely happy, in love and definitely wants to settle down,” a source explained.
Earlier this month, Reese revealed her parents approve of her relationship with 39-year-old Jim and hoped she would tie the knot again soon.
“My mom always texts me, like, ‘Are you getting married?’” the actress told Entertainment Weekly. “I’m like, ‘Mom, come on! You would know if I was getting married.’”