The pair attended The Paddy Wallace Fund for Autism Christmas Ball in Titanic Belfast, where celebrity guests queued to congratulate them.
"Everything in my life is going great," Rory (26) said, looking fresh despite his recent eye surgery. "I'm happy with how the season ended - and how the year has ended."
Sporting heroes including Tommy Bowe, Stephen Ferris and Iain Henderson rubbed shoulders with showbiz stars such as James Nesbitt - spotted in a dapper pork pie hat - and broadcaster Gerry Kelly. Also there was Tyrone GAA boss Mickey Harte, MP Ian Paisley, Northern Ireland manager Michael O'Neill and former international Jim Magilton.
Speculation about Rory and Erica (27) taking their relationship to the next level reached fever pitch last week after it was reported he had popped the question on a trip to Paris.
Last night, pals rushed to shake the golfer's hand after he revealed that the rumours about the engagement were true.
Rory was previously engaged to Danish tennis star Caroline Wozniacki, but he broke it off in 2014 after wedding invitations had been sent out.
Rory and Erica met when she came to the golfer's rescue at the Ryder Cup at Medinah in October 2012. The golfer mixed up his tee time and was only saved from disqualification after she noticed his error and arranged a police escort to the course. They were then spotted as a couple nearly a year ago, with the pair ringing in the New Year in style at Ashford Castle in Co Mayo.
Since then, Erica has become a regular sight on the course as she shows her support for Rory.
She formerly worked for the Professional Golfers' Association of America, and lives in Florida.
The Paddy Wallace Fund for Autism, set up by the Ulster rugby star and his wife Tina, aims to raise awareness of the condition and support families and children awaiting diagnosis or who have been diagnosed as being on the autism spectrum.