Sharma was commissioned into the 8th Battalion, 19th Hyderabad Regiment, in 1942. He served in Burma during the Arakan Campaign of World War II, for which he was mentioned in despatches. Fighting in the Indo-Pakistani War of 1947-1948, Somnath Sharma was killed in action on 3 November 1947 while repulsing Pakistani infiltrators near Srinagar Airport. For his gallantry and sacrifice during the Battle of Badgam, he was posthumously awarded the Param Vir Chakra.