In a speech at Atlanta's Emory University, Rushdie called the book and movie nothing more than "feel-good".
He also complained about various portions of the narrative, from how characters manage to acquire a gun in India to how they mysteriously wind up at the Taj Mahal, 1,000 miles away from the previous scene.
This isn't the first time that "Slumdog Millionaire" has felt the lash of Rushdie's tongue, Examiner.com said, noting that in January he told the New York Times: "I'm not a very big fan of 'Slumdog Millionaire'."
"I think it's visually brilliant. But I have problems with the storyline. I find the storyline unconvincing. It just couldn't happen. I'm not adverse to magic realism but there has to be a level of plausibility, and I felt there were three or four moments in the film where the storyline breached that rule," he said.
"The Reader" and "The Curious Case of Benjamin Button" - other movies that bagged Oscar trophies - didn't fare any better with Rushdie.
In his Sunday night speech, he called "The Reader" "a leaden, lifeless movie killed by respectability", and said that "The Curious Case of Benjamin Button" "doesn't finally have anything to say".
"Is Rushdie simply suffering from an unacknowledged book-to-film aversion?" the publication asked and suggested: "Actually, no. In 2004 he was a vocal supporter of 'The Lord of the Rings: The Return of the King' and he adored 'The Dark Knight'."
"Hurrah to Mr. Rushdie for holding fast to his literary and film principles. However, the ultimate test is yet to come," The Examiner said, noting that Rushdie's award-winning "Midnight's Children" is in the process of being made into a movie by director Deepa Mehta.