The Teddington-born actress looked as stunning as she did on her big day, donning the strapless, pale pink Rodarte ballerina-style dress.
Giving her favourite little number a special twist, Keira added a sheer overlay with cream embroidered beading on the collar and the cuffs. The Atonement star kept her look fresh with bare legs and strappy gold heels.
Keira was joined by her husband of seven months, James Righton, at the SeriousFun Gala which took place at London's Roundhouse. The Klaxons band member looked dapper in a dark tuxedo and bow tie, and lovingly embraced his wife on the red carpet.
Apart from wearing the Chanel design at her nuptials, when she paired it with a matching white Chanel tweed jacket, Keira had sported the frock long before her May wedding.
The 28-year-old was first spotted wearing it at a pre-BAFTA party back in 2008, making Tuesday's occasion the second time she has worn it at a red carpet event.
Before tying the knot, Keira had hinted that she wasn't going to spend her time on a lengthy hunt for the perfect gown.
"I don't need to have all that," she said. "I'm just trying to enjoy the engagement bit."
"It really depends on what sort of wedding I decide to have – if I go with a jeans and T-shirt option, then maybe it wouldn't be quite right."