Dilip Ruwan gained his first international experience at the 2015 Military World Games in Mungyeon , South Korea , where he finished fifth in the Sri Lankan 4 x 400 meter relay in 3: 08.65 minutes and the semi-finals in the 400 meter run reached in which he retired with 47.79 s. The following year he won the bronze medal in the individual competition at the South Asian Games in Guwahati in 47.30 seconds behind the Indians Arokia Rajiv and Kunhu Muhammed and in the relay he won the silver medal in 3: 07.59 minutes behind the team from India. The following year he finished fifth at the Asian Championships in Bhubaneswar in 46.50 seconds over 400 meters and won the silver medal behind India in 4: 04.80 minutes in the relay.
In 2016, Ruwan became the Sri Lankan champion in the 400-meter run.