"It's been a rough couple years," the 25-year-old wrote on Instagram, adding that he was also suffering from a chronic viral infection.
The star said he was aware of social media speculation that he had a drug problem, after he was pictured looking unwell with blotches on his skin.
He said he was getting "the right treatment" to help address the disease, and that more would be revealed in an upcoming YouTube documentary series about his life.
"You can learn all that I've been battling and OVERCOMING!!" he wrote, telling his 124 million Instagram followers: "I will be back and better than ever".
Lyme disease is caused by bacteria carried by some species of ticks.
The symptoms often include a rash, muscle pain, and tiredness.