"I was just so happy when she told me [about her engagement to Ryan Reynolds, 31]," said designer Roland Mouret – who just saw the actress at Monday's Metropolitan Museum Costume Institute Gala in New York.
"It's something she's really wanted – to meet someone and get married," he added, speaking to PEOPLE at the Vogue magazine launch of Tim Walker's portraits in London. "She's just such a great person and I'm so happy for her and wish her every happiness. She deserves it."
Mouret and Johansson first met when she was filming in London in 2004 and stopped by his studio. The 23-year-old then helped put him on the A-list fashion map by wearing his coral taffeta gown to the 2005 Golden Globes, followed by a black Mouret number to the Academy Awards.
But if you're handicapping the Johansson wedding dress design sweepstakes, don't include Mouret.
"No, no – it's not me," he said, laughing.
Still, the fashion-forward Johansson will have no shortage of options when it comes to her gown. In fact, Stella McCartney has already volunteered for the job.