McDowall was voted the winner of this year's Britain's Got Talent over the bookies' favourite Ronan Parke this weekend, and Mulhern claimed that he always felt the singer was an outsider on the show.
"I forgot that Jai was even in the competition," Mulhern admitted on This Morning earlier today.
"He was like the underdog," Mulhern explained. "You only saw him a couple of times."
The presenter also said that he thought recent claims the competition was fixed in Parke's favour may have helped McDowall to secure the overall victory.
"Do you know something, I don't think it helped," Mulhern added. "If people are going to be influenced by what they read, and we all know they are, of course it's not going to help."
McDowall, who also appeared on the show, said that he is due to begin the Britain's Got Talent tour soon, following which he will sit down with Simon Cowell and begin planning his career.
> Britain's Got Talent final: Pictures