Bang Rak is one of the fifty districts (khet) of Bangkok, Thailand. It lies on the eastern bank of the Chao Phraya River, beyond Khlong Phadung Krung Kasem, which marked the old city boundary. Originating from riverside settlements dating from before the city's foundation, Bang Rak grew inland as new roads and canals were constructed through the area during the second half of the nineteenth century and the early twentieth, attracting communities of expatriates and developing into a major commercial district. Bangkok's rapid economic growth in the late twentieth century saw the areas along Si Lom and Sathon roads transformed into one of the city's main business districts, teeming with skyscrapers. The district, officially recognised at least since 1908, covers an area of 5.54 square kilometres (2.14 sq mi), and has a registered population of 48,227. Today, Bang Rak is known for the financial activity of its commercial offices, as well as its vibrant nightlife scenes. Diverse historic and religious sites, most significantly concentrated in Bang Rak Subdistrict on the waterfront, reflect the district's multicultural history.

The Chao Phraya is the major river in Thailand, with its low alluvial plain forming the centre of the country. It flows through Bangkok and then into the Gulf of Thailand.