Nepenthes lamii is endemic to the higher peaks of central Papua province in West Papua, New Guinea, including Doorman Top (also known simply as Mount Doorman) and Mount Erica of the Hellwig Mountains. Sizable populations of this species have been found near Tembagapura, a mining town situated at around 1900 m in the Sudirman Range. Nepenthes lamii has an altitudinal distribution of 1460-3520 m above sea level. The uppermost altitudinal limit of this species represents the highest known elevation of any Nepenthes, although Nepenthes sp. Papua has been found at similar altitudes of around 3500 m.