Sampath Tennakoon was born on 20 June 1959. He was from Isipathana College, Colombo.
He was married to fellow actress Rathna Lalani Jayakody. They first met during a stage drama Puthra Samagama and then in Suba Sandewak. They have acted in more than 50 stage dramas together. Geetha Kanthi Jayakody is the sister of Rathna Lalani, who is a renowned award-winning actress in Sri Lankan cinema, theater and television. Popular actress Paboda Sandeepani is the daughter of her sister Geetha Kanthi. Popular actor Bimal Jayakody is the son of Rathna's elder brother. Bimal is married to fellow actress Sujani Menaka.
Tennakoon died on 3 December 2021, at the age of 62.He usually went to Lumbini Theater to watch stage dramas. He first acted in play Guru Lipi directed by Dayaratne Ratagedara and then in Ambu Samiyo by Douglas Siriwardena. He acted in teledramas such as Sneha,Verona and Maha Viru Pandu.
In 2013, Rathna and Sampath organized a drama festival titled Abhinayana Sampath-Rathna Rangabhumika to celebrate their 30 years in stage drama career. They staged seven popular dramas from 17 to 23 December 2013 at New Town Hall, Colombo 7, which they together acted.
