Shivantha has worked on stage, film and TV during his school years in Sri Lanka, Hong Kong and Australia. After completing both his Bachelor of Arts and Bachelor of Laws in Melbourne Australia, he studied at the American Academy of Dramatic Arts in New York, and was invited to become a member of the 2010-2011 Company.

Some of his roles at the Academy include Kent from Neil Labute’s Reasons to be Pretty, Mike from Escape from Happiness by George F. Walker, Talthybius from Trojan Women by Euripides. TV credits in Australia include The Librarians (ABC), Carla Carmetti (SBS), Kath and Kim (ABC).

Short films include Love and Iced Tea, Osama's Taxi, I Miss My Mind the Most, Houseguests, Jack and Dan, Love Is…, Lying in the Blaze, Hechki, Dim Sum, Old Habits Die Hard and A Walk on Cutter's Ridge.

In 2011, he worked with Cathy Scorsese on her project Campus Life, and in October 2012, he was selected by Marci Phillips from ABC, for the annual ABC Variety Showcase that premiered in NY - out of 7500 applicants, only 12 were selected. 

In 2012, he won the award for the Best Supporting Actor at the Asians on Film Festival in Los Angeles, for his performance as Jeffrey in Michael Cutrone's Find Them. 

The short film A Lotharoio's Lament, directed by Sheila Mitchell Simmons, was accepted into Cannes Film Festival earlier in 2014. 

He is currently working on the feature film Out of My Hand, with director Takeshi Fukunaga:

In 2014, he will be making his Off Broadway debut, in Tom Stoppard’s Indian Ink at the Roundabout Theater with Carey Perloff later this year.