Durbin, 22, who was widely seen as a sure bet for going all the way to the finals, got the least number of votes despite universal praise from the judges during the week of inspirational songs.
His shock departure left 17-year-old country singer Scotty McCreery, pop/country singer Lauren Alaina, 16, and Haley Reinhart, 20, to compete for a place in the finale.
"I worked so damn hard and I was hoping to get there," said a stunned Durbin, tears streaming down his face.
"But I did so much stuff that's never been done on the show. I did what I came here to do, and that was to give metal a chance," he declared.
Durbin, who suffers from the tic disorder Tourette syndrome and describes himself as a high-functioning autistic, made a name for himself on the top-rated show with a series of hard rock performances, often against the advice of in-house mentor Jimmy Iovine.
But on Wednesday's performance show it was Reinhart who got a big thumbs-down for her rendition of the Michael Jackson's "Earth Song." In an unusually harsh remark, judge Randy Jackson chided Reinhart for "screaming."
For all the controversy earlier this season about audience bias toward male contestants, the final three is now made up of two women and a sole man.
"Idol" has increased its audience this year after three years of slipping ratings, thanks mostly to the arrival of new judges Jennifer Lopez and Aerosmith rocker Steven Tyler.
Tyler on Thursday debuted the music video of his first U.S. solo single -- a pop-heavy song called "(It) Feels So Good."
The 2011 "American Idol" finale airs on the Fox network on May 24 and 25, when viewers will choose the winner, and he or she lands a recording contract.
Past winners Kelly Clarkson and Carrie Underwood have gone on to major singing careers, while eliminated finalist Jennifer Hudson won an Oscar for her supporting role in the big-screen adaptation of the "Dreamgirls" musical.