The Office star, 29, and actress, 26, who have been dating since November 2008, are engaged, his rep confirms to PEOPLE.
“We can confirm that John and Emily are engaged,” says the rep.
The couple have kept their relationship under wraps, arriving separately at the 2009 SAG Awards in January and enjoying low-key dates in Los Angeles – including a double date with Blunt’s The Devil Wears Prada costar Anne Hathaway and her beau Adam Shulman.
“It’s not about celebrity or not,” Krasinski told Glamour in August 2007 about what he looks for in a woman. “It’s all about, do you have that ‘girl in a cardigan’ in you. You gotta have that.”
Krasinski, named one of PEOPLE’s Sexiest Men Alive, also said he looks for someone with a good sense of humor.
“Being able to laugh with someone is one of the best feelings,” he told PEOPLE last year.
Krasinski previously dated his Office costar Rashida Jones. Blunt ended her relationship with Canadian singer Michael Bublé in July 2008 after three years of dating.
• Reporting by JULIE JORDAN
• See John’s ‘Sexiest Man Alive’ spread!