The woman went to police in the west coast nightlife hub after both men had sex with her at a Patong hotel.
Police arrested Theerasak Bootcha, 26, late on Wednesday. He admitted the rape, police said.
The woman told officers at Kathu Police Station in Patong that she and two Thai male friends had been out enjoying themselves on Wednesday morning.
The three friends had been drinking at the Grabana Grus Nighclub. The Soi Bangla nightclub closed at 2am and they drank for a little longer.
Soon after, one of the Thais, Theerasak, a former nightclub security guard, took the expat back to a hotel where the pair had sex.
He then telephoned a friend who came to the hotel and also had sex with the woman, police have been told.
The woman told police that she knew Theerasak and consented to have sex with him but did not choose to have sex with his friend.
The men threatened her with violence if she did not comply. Police say security camera footage from the hotel supports the woman's account.
After going to police about 4.30am the woman was taken to Patong Hospital with a woman international volunteer assisting police in their investigation.
*The woman was originally reported to be from Australia but it's now believed that she is from Europe.