The 29-year-old singer checked into a treatment centre to "improve his health and work on his overall wellness", but left last week after spending just two weeks in the facilities care in order to deal with some unspecified "legal and personal matters".
However, his publicist Steve Honig has now revealed that on Saturday evening, Aaron returned to rehab to complete his treatment, now that the matters in question have been resolved.
Speaking to People magazine, he said: "Aaron has taken care of the legal and financial matters that required his attention and returned to the wellness facility to complete his program."
Representatives for the 'I Want Candy' hitmaker revealed on September 22 the star had checked into rehab, and insisted he was working on "coming back stronger than ever before".
They said in a statement "Aaron has decided to enter a facility to improve his health and work on his overall wellness. He is going to do this privately and focus all his attention on being the best person and performer possible. He is grateful for the support and love from his fans and looks forward to coming back stronger than ever before."
Aaron's decision to enter rehab came after he previously admitted he was "concerned" about his "overall health."
He explained: "I'm concerned about my overall health because people tell me I look like I have AIDs or I look like I have cancer or I look like I'm dying."
And it seems as though his brief time in the treatment centre had worked, as after leaving the facility, Aaron took to social media to show off his healthy 30lbs weight gain.
Alongside a split image of his body before and after, he said: "From 115 pounds to 145 In a few weeks. On the left 115 on the right 145 Continuing to focus on myself and my health. Sorry I couldn't wait to show you till 2018 #proudofmyself #StressFree I missed you all so much. Needed some time to heal and this is a direct result. (sic)"