Sundarrajan is a South Indian surname. Notable people with the surname include:
Major Sundarrajan (1935–2003), Tamil actor R. Sundarrajan (born 1950), Tamil director and actor R. Sundarrajan (politician) (died 2020), Indian politician
See also Sundar Raj (active 1967–present), Indian actor R. Sunder Raj, aka Sunder Raj or Sundar Raj, Malayalam film producer, known for the 1933 silent film Marthanda Varma Sunder Raj, an Indian fisherman who was killed in 2006 by Sentinelese people