Khaosan Road or Khao San Road ) is a short (410 meter long) street in central Bangkok constructed in 1892 during the reign of Rama V. It is in the Bang Lamphu area of Phra Nakhon District about 1 kilometre (0.62 mi) north of the Grand Palace and Wat Phra Kaew.

"Khaosan" translates as 'milled rice' or 'rice mill', a hint that in former times the street was a major Bangkok rice market. In the last 40 years, however, Khaosan Road has developed into a world-famous "backpacker ghetto". It offers cheap accommodation, ranging from "mattress in a box"-style hotels to reasonably priced three-star hotels. In an essay on the backpacker culture of Khaosan Road, Susan Orlean called it "the place to disappear." According to the Khao San Business Association, the road sees 40,000-50,000 tourists per day in the high season, and 20,000 per day in the low season.

The area is internationally known as a center of dancing, partying, and just prior to the traditional Thai New Year (Songkran festival) of 13–15 April, water splashing that usually turns into a huge water fight. One Thai writer has described Khaosan as "...a short road that has the longest dream in the world".

In July 2018, the Bangkok Metropolitan Administration (BMA), in an attempt to clean up Khaosan Road, announced that street vendors would be removed from the thoroughfare from 1 August 2018. The BMA intends to move them to a nearby area and restrict their trading hours to 18:00 to midnight. The Khaosan Street Vendors Association, representing some 300 vendors, rejected the move, citing financial ruin for vendors. Last-minute negotiations between the BMA and vendors proved fruitless as neither side has been willing to compromise. Khaosan vendors announced that, in defiance of BMA order, they will open as usual on 1 August. On the first day of the ban on stalls, roughly 70 percent of the vendors opened as usual in defiance of the police.

The BMA announced in 2019 that it will commit 48.8 million baht to transform Khaosan Road into an "international walking street". The US$1.6 million project, the first makeover of the road since its creation in 1892, will commence in October 2019, continue through the tourist high-season, and be completed by February 2020.