"It was an outdoor ceremony and absolutely beautiful," an insider tells Us. George Clooney and Italian girlfriend Elisabetta Canalis were in attendance; Blunt and Krasinski had been staying at Clooney's nearby Lake Como estate since the July 4th weekend.
"It was an official ceremony. They are husband and wife," adds the source.
After about a year of dating, "The Office" star Krasinski, 30, proposed to British actress Blunt, 27, with a 3-carat Edwardian diamond and platinum ring from Neil Lane, worth $100,000.
Krasinski told Access Hollywood that the proposal was "very casual" but very emotional, too. "She did cry after I cried, and we cried and then everyone around us was crying," he said.
"She's a wonderful girl," Krasinski gushed at last year's Emmys of his fiancee.
"So many people say, 'You know when you know,' and it's true," Krasinski added of his love. "It's all true."