The Lawn Tennis Association of Thailand announced on Thursday that the match will be part of the regular invitational event in Hua Hin, a popular holiday destination southwest of Bangkok.
Ms. Azarenka has twice played exhibitions matches there, while this will be Ms. Williams' first appearance at the event.
Williams will also be defending her title against Azarenka at next month's Brisbane International, among a powerful women's field in preparation for the Australian Open.
Williams' opponents at the Dec. 29 to Jan. 5 Brisbane tournament will include six of the world's top-10 players. The field announced Thursday includes Azarenka — the 2009 champion — Maria Sharapova, Jelena Jankovic, Angelique Kerber and Caroline Wozniacki.
Tournament director Cameron Pearson said "to have Roger Federer and Serena Williams headline the event is a remarkable result and testament to the high regard the players have for the tournament."