The singer/actor has proposed to Renee Puente and the happy news was announced during Sir Elton John's annual White Tie and Tiara Ball in London on Thursday (27Jun13).
Sir Elton then teamed up with Coldplay frontman Chris Martin to perform a duet of Your Song in the couple's honour.
A source tells E! News, "They are thrilled... He loves her so much. The theme of the night was love, which is so appropriate."
The revelation at the event was especially poignant for the pair - the actor debuted Puente as his girlfriend at the 2011 bash.
Morrison gushed about his now-fiancee in a recent interview with Britain's Cosmopolitan magazine, declaring, "She's amazing... I've chosen to be with her and I'm happy. I still want to marry and have kids one day. And when I'm ready to propose, she'll be the first to know."
The star was previously engaged to soap opera actress Chrishell Stause.