Longyearbyen is located in the Longyear Valley, which is just off the Adventdalen valley. The Adventfjorden runs along the southern shore of the valley. The population of Longyearbyen is around 2,500, with the largest group of Norwegians coming from Northern Norway (they make up 40% of the population). Roughly 300 people are non-Norwegians, with the largest nationalities being from Thailand, Sweden, Russia and Ukraine. Because of the mining industry, around 60% of the population are male. The average age of the population is between 25 and 44 years old, and there are nearly no residents over the age of 66.

Longyearbyen experiences a high turnover, with the average person living there for 6.3 years (6.6 for Norwegian and 4.3 for foreigners). The longest-residing people in the town tend to work in mining, followed by government employees. The shortest tenures are students and employees in higher education, tourism and the state.

70% of households consist of a single person, compared to 41% on the mainland. This is because many people work on Svalbard while their family remains on the mainland.

Coal production peaked in 2007, but today there is only one mine operating. Fishing is a growing economy as fish flee the warmer waters of the south in Norway (thanks to climate change) and head north to Svalbard. The University Centre of Svalbard has 350 students and 40 professors. Tourism is also very important.