Katie screnshotted a message she had received from an online user and posted the crude message to her Instagram account.
Since this message was sent directly to the mum-of-five, Katie has shared various screenshots of online users who have been making fun of Harvey, 13, saying she's "on a mission to stop this happening."
Katie uplaoded the sexually abusive message screengrab, and commented:
"Can everyone help report this sick twisted man and if you know him give me details please he needs to be named and shamed and be questioned and clearly shouldn't be roaming around with thoughts like that about a child."
Harvey, Katie’s first child from previous relationship with Dwight Yorke, suffers from Prader-Willi syndrome, as well as autism, ADHD and blindness.
Various online trolls have mocked his condition and ethnicity, with Katie posting to Twitter to bring attention to the unpleasant taunts.
It was only last week that 37-year-old Katie had to defend herself after admitting on Loose Women, that if she had known about Harvey’s disabilities during pregnancy, she would have had an abortion.