The 44-year-old, who is engaged to Justin Theroux, wore a plum coloured pencil dress that flaunted her fabulously toned figure and a more rounded tummy than usual.
She teamed the Burberry gown with sky-high suede heels and one show stopping accessory – her dazzling emerald-cut diamond engagement ring, rumoured to be eight carats.
The former Friends actress showed off a healthy summer glow and beamed for photographers as she posed on the red carpet.
She was joined by her co-stars Emma Roberts, Jason Sudeikis and his fiancée Olivia Wilde among others.
Jen's fiancé Justin wasn't on the red carpet but joined her afterwards for the glittering afterparty.
The couple, who got engaged on Justin's birthday on 10 August 2012 after dating for more than a year, have not set a wedding date.
During the New York press conference for the comedy flick, the actress revealed that the couple are in no rush to walk down the aisle.
"We just want to do it when it's perfect, and we're not rushed, and no one is rushing from a job or rushing to a job," she explained.
"We have yet to set any date. There have been no cancelled weddings. There have been no postponed weddings. There have been no arguments about where to get married. Just clearing all that up."
It remains to be seen whether the pair will start a family but Jennifer has made it clear in the past that children are on the cards.
"I've said it so many times: I'm going to have children," she told US Vogue in 2008. "I just know it."