Nepenthes ovata is endemic to a number of mountains in North Sumatra, particularly in the Lake Toba region. It grows in stunted mossy forest and ridge top vegetation, often among Sphagnum moss. On Mount Pangulubao, the species usually occurs terrestrially, while on Mount Lubukraya it often grows as an epiphyte. It has also been recorded from Mount Simanukmanuk. The species has an altitudinal distribution of 1700-2100 m above sea level.