Swift's "You Belong With Me" clip beat out Beyonce's "Single Ladies" in the best female video category.
As Swift, 19, was expressing her thanks for the honor, West took the stage, grabbed the microphone away from her and proclaimed Beyonce's video one of the best of all time. His behavior prompted booing from the crowd.
"I'M SOOOOO SORRY," West later said on his blog, admitting he was "in the wrong for going on stage and taking away from her moment."
"Beyonce's video was the best of this decade ... I'm sorry to my fans if I let you guys down ... I'm sorry to my friends at MTV ... I will apologize to Taylor. ... I really feel bad for Taylor and I am sincerely sorry."
Usmagazine.com said Swift told reporters after the show she didn't intend to hold a grudge against West, who the magazine said was seen drinking from a Hennessy liquor bottle throughout the night.
"I don't want to start anything because I had a great night tonight," Swift said.
Upon later winning the evening's top award for video of the year for "Single Ladies," Beyonce invited Swift back on stage to finish her acceptance speech, which she did.
Rolling Stone magazine collected an assortment of memorable online quotes from other musicians bashing West's behavior.
Katy Perry fumed via Twitter: "(Expletive) U Kanye. It's like u stepped on a kitten."
"I've seen you do some pretty (expletive) things, but you just keep amazing me with your tactless, (expletive) ways. It's absolutely fascinating how much I don't like you. I like everyone," Kelly Clarkson said on her IAmKelly blog.
Pink, who reportedly was stopped by security as she tried to tell West what she thought of him in person, Tweeted: "Kanye West is the biggest piece of (expletive) on earth. Quote me. My heart goes out to Taylor Swift. She is a sweet and talented girl and deserved her moment."