The 44 year old former Today presenter claimed to fans that his account had been hacked and the incident was being investigated by the authorities.
But instead of the sympathy he was hoping for, internet trolls claimed they accused the father of two for making it all up.
'Did you get p**ed and go rogue again? Classic you,' wrote one.
'I don't believe it for a second' commented another.
And the comments continued with some saying: '[That] sounds like something fake Karlos would say'.
'Yeah right, somebody gained access to your account and the only thing they did is like a couple of comments...' said another.
Other fans joked that it could have been the 'Russians' that instigated the hack and some suggested that Karl should investigate the matter on 60 Minutes.
The flurry of comments come after Karl said that someone had hacked his account while he was out fishing as a response to an article in the Daily Mail.
'While I was out fishing my Instagram account has been hacked. I am investigating this with the authorities and will be back soon. Karlos,' he wrote.
His statement came after his account 'liked' several comments mocking the Today Show lineup, including:'Won't be watching. Well, Miss Gardiner [sic] got her way. Pathetic, smile, agree and laugh. It's all they do.'
And 'Channel [Nine], the audience want answers.'