The pop star twins, whose real names are John and Edward Grimes, tweeted the scathing condemnation of their former X Factor mentor after Walsh announced plans to launch a new girl band.
On Sunday (13 June), Walsh revealed that he is looking for “young, exciting new girl singers” this autumn for a proposed band.
In response, Jedward first republished quotes from an interview Walsh gave to The Irish Independent, in which he recalled advising members of Girls Aloud to lose weight.
“They were competing with the Spice Girls,” Walsh said. “It matters for them because they all want to be the skinny bitch in the middle going out with the footballer.”
“Don’t get involved with Toxic Management!” Jedward tweeted.
In a second tweet, the pair added: “Louis Walsh at this point only wants acts to manage to make it look like he’s doing something! He’s a cold hearted two faced bitch who uses his powers for his own benefit!”
The Independent has contacted Walsh’s representatives for comment.
Walsh acted as Jedward’s mentor during their star-making appearance on The X Factor in 2009, and served as their manager in the immediate aftermath of the show. It is unclear when Walsh and the pair stopped working together.
In April, Jedward launched into a fiery tirade against Walsh’s fellow X Factor star Simon Cowell, with the twins tweeting that their biggest regret was “not telling the judges on X Factor to f*** off”.
Watch: Why Jack Savoretti and his band dressed up to record their new album Europiana