The name Ko Pha-ngan derives from the word "ngan", meaning "sand bar" in the southern dialect, for there are many sand bars offshore.
Ko Pha-ngan has been a longtime favorite of past kings of Thailand. Rama V, or Chulalongkorn, for example, visited Ko Pha-ngan 14 times during his reign.
The Bronze Drum of Dongson Culture (500–100 BCE) that was found on Ko Samui in 1977 is evidence that there were settlements of people on Ko Samui, Ko Pha-ngan, and their islets more than two thousand years ago. Some historians and archaeologists believe that the first group who migrated to Ko Pha-ngan were the Muslim sea gypsies (Pygmy, Semung, and Proto-Malay) who travelled by boat from the Malay Peninsula. Today there are few Muslim inhabitants.
Over the last century the island's population has steadily expanded, first living off the sea and the land and farming coconuts. Later, tin mining became part of the economy. In the 1970s the mining industry faltered and finally petered out. Over the next decade tourism took hold. Now the island is primarily a tourist destination. Fishing and coconut farming remain important to the local economy.
Due to its topography, the population hugs the coastline. The mountainous interior is generally inaccessible. More than half the island designated as national park and Ko Pha-ngan has more than 80 km2 (31 sq mi) of relatively unspoiled rain forest with diverse flora and fauna. It is also considered a spiritual place, with numerous Buddhist temples around the island and a thriving spa, retreat, and meditation industry.
Visitors to the island can only reach it by seagoing ferry, either from Surat Thani, 55 km distant, or Ko Samui, 15 km away. Since 2012 Kannithi Aviation (Kan Air) has attempted to construct an airport. Kan Air has spent some 500 million baht to acquire about 32 hectares of land to build a passenger terminal capable of handling 1,000 passengers a day and a 1,095 metre runway to accommodate turboprop aircraft such as Kan Air's ATR 72-600 series. The project, originally estimated at 900 million baht — now estimated to cost two billion baht — has faced inflated costs, delays resulting from the yet-to-be-issued environmental impact assessment and other complications, which pushed back initial plans to open in 2014. According to Kan Air's president, the airport will open by the end of 2017.
Ko Pha-ngan together with Ko Tao forms the district (amphoe) Ko Pha-ngan (148 km2. The district is divided into three sub-districts (tambon):
Originally the island was administered from Ko Samui District. The minor district (king amphoe) Ko Pha-ngan was established on 1 October 1970, then consisting of the two tambon, Ko Pha-ngan and Ban Tai. It was upgraded to a full district on 12 April 1977.
Parts of the tambon Ko Pha-ngan and Ban Tai form the township (thesaban tambon) Ko Pha-ngan. There are an additional three tambon administrative organizations (TAO).
Ko Pha-ngan featured prominently in Alex Garland's 1996 novel The Beach and is also mentioned in the 2006 song Magick by the new rave band Klaxons (but probably more as a reference to the 1996 novel The Beach than the island itself).
The Full Moon Party is a monthly dance music festival set on Haad Rin Nok Beach scheduled every month at full moon. The event primarily features electronic music and attracts around 30,000 party-goers in a normal month. Recently steps have been taken to make Ko Pha-ngan into a more family-friendly tourist destination, promoting the island's wealth of natural attractions and also stepping up the police presence; road blocks with stop and search procedures are commonplace and undercover police also patrol parties.
There is also a Half Moon Party held every month at half moon. While the full moon party takes place on the beach at Haad Rin Nok, the half moon party takes place in the jungle inland from Ban Tai, requiring Tuk-Tuk, taxi or bike transport to and from.
The song "Vision in Blue" on the album The Golden Ratio by Ace of Base mentions Ko Pha-ngan.
DJ/producer Ashley Wallbridge titled his 2012 song "Kopanang", an anglicized version of Ko Pha-ngan.
The British psychedelic rock band Ozric Tentacles featured a song called Ko Pha-ngan on their 1989 album The Bits Between The Bits.
In 2016, Infected Mushroom collaborated with Hatikva 6 to release a song called "Hotel Koh Phangan."