Watthana or Vadhana, Thai: วัฒนา; IPA: [wát.tʰā.nāː]) is one of the 50 districts (Khet) of Bangkok, Thailand. Neighbouring districts are (from the north clockwise): Ratchathewi, Huai Khwang, Suan Luang, Phra Khanong, Khlong Toei, Sathon and Pathum Wan.
Watthana became a separate district by a split from Khlong Toei in 1998 to provide better service to its population. The district obtained its name from Princess Galyani Vadhana, the elder sister of King Bhumibol Adulyadej. Watthana or Vadhana means development. The area is among the most developed parts of Bangkok.
On 1 January 2009, Watthana was the location of the Santika Club fire, which killed 66 and injured 222.
The district is sub-divided into three sub-districts (Kwaeng), from west to east:
Comprising the area between Sukhumvit Road and Khlong Saen Saeb, Watthana is one of the commercial districts in Bangkok with lots of condominiums and hotels. A lot of expatriates of many nationalities live there.