Vinayagamoorthy was a long-standing member of the
All Ceylon Tamil Congress (ACTC). He was one of the ACTC's candidates in
Jaffna District at the
1989 parliamentary election but the ACTC failed to win any seats in
Parliament. He took on the leadership of the party following the assassination of
Kumar Ponnambalam in January 2000. He was the ACTC candidate for Jaffna District at the
2000 parliamentary election. He was elected and entered Parliament. He relinquished leadership of the ACTC to Ponnambalam's son
Gajendrakumar Ponnambalam when he entered politics in 2001. On 20 October 2001 the ACTC,
Eelam People's Revolutionary Liberation Front,
Tamil Eelam Liberation Organization and
Tamil United Liberation Front formed the
Tamil National Alliance (TNA). Vinayagamoorthy contested the
2001 parliamentary election as one of the TNA's candidates in Jaffna District. He was elected and re-entered Parliament. He was one of the TNA's candidates in
Vanni District at the
2004 parliamentary election but failed to get elected after coming sixth amongst the TNA candidates. Gajendrakumar Ponnambalam left the TNA in 2010, taking the ACTC with him but Vinayagamoorthy stayed with the TNA. He was one of the TNA's candidates in Jaffna District at the
2010 parliamentary election. He was elected and re-entered Parliament. He was not chosen to contest the
2015 parliamentary election. ==Electoral history==