Nilson was born in Stockholm, Sweden. He has completed 28 expeditions, visiting around 100 countries. When he is not on expeditions he gives lectures about motivation and environmental awareness.
After participating in some film work with the Polar Research Team, Nilson began collaborating with Respect Climate. In 2008 he finished his project “Seven Summits Climate Neutral”. After the first Climate Neutral Everest expedition, Nilson was elected Swedish President of the Everest Summiteers Association (ESA), and a member of The Explorers Club.
He received the Medal of Honour from the Swedish Church in 1996. He is a member of the Royal Swedish Academy of Sciences, and received the Orden of Amaranter, the Royal Orden founded by Queen Krinstina.
Nilson has completed exhibitions in Africa and Antarctica, as well as to the mountains Mount Denali (1995), Mount Kilimanjaro (2003), Mount Elbrus (2004, 2008), Mount Aconcagua (2005, 2006), Carstensz Pyramid (2006), Mount Everest (2007), Mont Blanc (2006, 2007), Mount Vinson (2008), Mount Kusciuskzo (2006), Shisha Pangma (1997), Mount Kinabalu (2000), and Heidi Hill Nunavut (1999). His mixed expeditions include the Alaska Walkabout Expedition (1995), Jetski over the Atlantic (2002), Machu Picchu (2005), the Arctic Dogsled Race (1999), and a Borneo Photo Expedition (2000).