He first started weightlifting under the guidance of his father, Mothilal Jayathillake and later he was coached by the former national weightlifting coach, Athula Wijewickrema.
He won a Bronze Medal at the Junior World Championships in 2002 and won a Silver Medal in 2003 at the same meet.
Ransilu secured the Gold Medal at the Commonwealth Championships in Canada in 2016, Gold Medal at the Singapore Open Grand Prix in 2014 and 2015, Gold Medal at the Asian Championship in Indonesia in 2016, Gold Medal at the Commonwealth Championships in South Africa in 2017, Gold Medal at the Asian Championships in India in the same year, Silver Medal at the Asian championships in Mongolia in 2018, Silver Medal at the Asian Oceania Championships in Australia in 2019 and Gold Medal at the Commonwealth Championships in Canada in 2019.
He was placed 16th at the World Powerlifting Championships in the US
In 2016, seventh place at the same meet in Belarus in 2017, ninth place at the same meet in Canada in 2019 and 14th place at the Championship held in Sweden in 2019.
Ransilu has created more than 50 Sri Lanka records and is the unbeaten national champion since 2002 upto date.