According to the LGBT news website PinkNews, the chart-topping artist published a string of offensive posts on Twitter between 2011 and 2014.
Responding to the claim, he acknowledged: "I said some foul and offensive things whilst tweeting years ago at a time when I was young and proudly ignorant... Very hurtful and discriminative views that I've unlearned as I've grown up and become a man.
"The comments I made were unacceptable and disgusting, full stop; comments that I regret and to everyone I've offended.
"I am sorry, these are attitudes I've left in the past.
The 24-year-old, who accepted a GQ award from Jeremy Corbyn in September, has become the latest among a number of celebrities to attract criticism for their language on social media.
YouTube star Jack Maynard recently left the reality television show 'I'm a Celebrity... Get Me Out Of Here!' to defend himself against accusations he used homophobic and racist language on Twitter.
Stormy said: "The homophobic language I used was, embarrassingly, a part of my vocabulary when I was younger and ignorance made me feel comfortable to use them whilst not understanding the hate and the ramifications they carry.
"That isn't an excuse, I take responsibility for my mistakes and hope you can understand that my younger self doesn't reflect who I am today.
"Again, I'm sorry to everyone I've offended.
"To the LGBQT community and my supporters and friends, my deepest apologies."