The Sunday Times reported Middleton will wear a dress designed by Burton, but when CNN asked a representative of the London design house for a confirmation she flatly denied it.
"This is not true," Alexander McQueen spokeswoman Myriam Coudoux said.
Burton and company chief executive Jonathan Akeroyd told the Times they deny the story.
Hongyi Huang, the head of press for McQ, the house's contemporary clothing line, also denied the report, CNN said.
Prince William's press office was mum on the subject.
"We're not commenting on the specific designer for the dress, because Catherine Middleton wishes to keep the designer a secret until the wedding day," Clarence House said Sunday.
Alexander McQueen, founder of the fashion firm that bears his name and who was one of Britain's most notable designers, committed suicide last year.