His father Reggie Mendis was a former member of the Central Committee of the Lanka Sama Samaja Party (LSSP).

Reggie's hand was broken near his wrist when he was hit by an oncoming bomb to protect Colvin R. de Silva.

[6] At the age of 29, Lakshaman started his career in 1985 acting in a documentary tele drama Gangulen Egodata directed by his friend Dr. Dharmasena Pathiraja.

The serial was telecast in 2016 in ITN where it became the highest rated crime television drama on IMDb database receiving a score of 9.9/10 in which resulted by majority voting 10/10.

[8][9] In 2016, he was invited to play the lead role in the biopic film Nidahase Piya DS directed by Suneth Malinga Lokuhewa.

When the director informed Mendis about the biopic, he was bit confused as he is a member of the left wing where Mendia politically had a problem.

[15][16] In 2020, he appeared in two television serials: Ahanna Kenek Na and Sudu Andagena Kalu Awidin, both received several awards at local festivals.