The ruling by the Court of Appeal in Bucharest replaces the latest period of custody, which was to end on 29 April.
Two associates, Georgiana Naghel and Luana Radu, are also being released.
All four have been ordered to stay in the buildings where they live, unless they have judicial permission to leave.
A spokeswoman for the Tate brothers told the BBC the brothers were “ecstatic”.
After being released, Andrew posted a video of himself pacing in a room while smoking a cigar, saying: “Since last year I’ve been in 24-hour lockdown. No yard time.
“Pacing a 3-metre cell with zero electronics or outside contact. Absolute clarity of mind. Real thoughts. Real plans. Vivid pain. One hour home and I can’t stand my phone.
“Some habits die hard. We must defeat Shaytan.”
Tristan, meanwhile, tweeted: “4 months without putting on a pair of alligator shoes. The struggle was real.”
The brothers have been detained since December. They are being investigated on allegations of rape, people trafficking and forming an organised crime group. Both have denied wrongdoing.
Lawyers for the Tates argued that keeping him them preventative custody was unnecessarily harsh, when other judicial options such as house arrest were available.
Leaked court documents, seen by the BBC, outlined testimony from alleged victims claiming to be forced to earn €10,000 (£8,800) a month on social media platforms, under the alleged threat of physical violence.
Court papers also described debts being used as “a form of psychological coercion”. Since investigations began last April, six women have been identified by prosecutors as victims.