"Nepenthes rajah" is classified as Endangered (EN – B1+2e) on the IUCN Red List of Threatened Species. It is also listed on Schedule I, Part II of the Wildlife Conservation Enactment (WCE) 1997 and CITES Appendix I, which prohibits international trade in plants collected from the wild. However, due to its popularity among collectors, many plants have been removed from the wild illegally, even though the species' distribution lies entirely within the bounds of Kinabalu Park. This led to some populations being severely depleted by over-collection in the 1970s and eventually resulted in the species' inclusion in CITES Appendix I in 1981. Together with "N. khasiana", it is one of only two species in the genus to feature on this list; all other "Nepenthes" species are covered by Appendix II.