The duo, who competed in the 2009 series of the competition, told Digital Spy that they want the singer to be crowned the winner in next month's final.
Describing her as "fresh", John Grimes said that Lily is "totally different" and could "offer a lot more" than the other singers in the competition.
The twins also said that they were disappointed by Kitty Brucknell's "crazy" exit from the ITV1 show last weekend.
"Kitty and Lady GaGa should become best friends. Kitty should go on a world tour with Lady GaGa," they said.
Meanwhile, discussing Frankie Cocozza's exit from the series following alleged drug use, Jedward said that they hoped the "cool" 18-year-old should "pick himself back up" and remain "calm, relaxed and stop doing what he's doing".
Jedward release new single 'Wow Oh Wow', the third track lifted from their Victory album, on November 20.
> Jedward, Tara Reid film Baywatch-themed music video for 'Wow Oh Wow'
> Jedward get goofy at 'Disney Universe' game launch: Pictures
Listen to 'Wow Oh Wow' below: