"The Hills" stars tied the knot in an impromptu ceremony on Nov. 20 at the One & Only Palmilla Resort near Cabo San Lucas, Mexico, Us Weekly reports.
"The minute we said our vows, I couldn't stop crying," Montag said.The publicity-loving couple surprised fans by keeping a lid on the news for several days, with Montag's rep telling the Daily News on Monday afternoon, "I do not have any information at this time."
Now, they're spilling the deets - and Pratt's even sharing the vows he recited to his wife.
PHOTOS: WHY ARE THEY FAMOUS AGAIN?
"Heidi, from the moment you came into my life, I knew my life would never be the same without you," he said.
"You are the light in my life like the sun to the earth! Your loving warmth makes me want to be a better person. Being with you, I feel complete. I'm honored to even be able to call you my wife. You are the most amazing, loving and caring woman on this planet. I will love you forever and always."
Montag, 22, and Pratt, 25, met in 2006 while filming the MTV reality show. They announced their engagement via the show in May 2007, before splitting in December. They became re-engaged in May 2008 after taking a Mexican vacation together.
"MTV wishes Heidi and Spencer the best and can't wait to share their special moment with 'The Hills' fans later this season," says an MTV spokesperson.
The couple's wedding photos will be published in this week's issue of Us Weekly.