The singer, who is among the Final 12 on the ITV1 reality show, appeared to be angry and annoyed about comments made by X Factor viewers.
"Who are these people on the Digital Spy forums!?!?" he wrote. "Do they have no idea that there nothing but negative lowlifes for even typing such s**t!?
"Some of these fools don't even realise how disgustingly ignorant and ridiculous there opinions are!! Get a life.
"I wouldn't normally rise to it but I'm in genuine disbelief that these clowns dare to write the s**t they write on there!"
Venting his frustration, he continued: "They should be locked up for some of the s**t they say about us lot.
"Rarely do I go on s**t like Digital Spy which is made for w**kers with no lives who wanna find out what's happening on Corrie next wk but when I do all I see is abuse! I reckon they should shut that s**t down!!"
He qualified his comments somewhat when fans of Arthur, who also use Digital Spy, contacted the singer.
"Maybe that was a bit of a generalisation, but all I meant was there is a lot of negative people on there by the looks of it," he added.
Digital Spy editor David Moynihan commented: "Like Twitter or Facebook, our forums are a platform where people can speak openly and freely about the topics that interest them. We are incredibly proud of our forums and the millions of users that enjoy them each month!
"We wish James the very best of luck during his time on The X Factor (we'll be watching every week) and would reassure him and others that our reactive moderation policy is clearly stated. Offensive content that breaches those rules is removed following reports and investigation.
"What we can't do, unfortunately, is make everyone like him."
The X Factor Live Shows kick off this weekend on ITV1.
Watch James Arthur's Judges' Houses performance below: