He started his career at an early age as a dubbing child artist. His father,
P. J. Sarma was a leading dubbing artist. Sai Kumar followed in his father's footsteps, having dubbed for
Suman and
Rajasekhar for many of their films. As a child actor, he appeared in
Devudu Chesina Pelli (1975) and
Sneham (1977). He resumed acting as an adult, appearing in
Challenge (1984),
Kalikalam (1991),
Major Chandrakanth (1993) and others. He started in Tamil movies like
Thaiyalkaran (1991),
Kaaval Geetham (1992),
Vaettiya Madichu Kattu (1998) and then the action roles such as
Aathi (2006),
Thenavattu (2008) and
Thiruvannamalai (2008). He appeared in the 1996 Kannada film
Police Story, which was also voice dubbed in Telugu and Tamil. His Kannada films
Agni IPS (1997),
Central Jail (1997),
Police Story 2 (2007) were all major hits at the box office and Sai Kumar became a household name in Karnataka. Sai Kumar says, 'I am indebted to Karnataka for making me a star and giving me
Police Story during my struggling days.' and his performance in the film was not only praised by the critics, but also earned him an
IIFA Utsavam and
SIIMA Award. He produces his son's film
Aadi titled
Garam (2016). In 2019, the brothers Sai Kumar,
Ravi Shankar and Ayyappa to play a major role in
Sriimurali starrer
Bharaate. After essaying a number of amazing roles as a male protagonist and a character artiste, Sai Kumar makes
OTT debut with
Gaalivaana (2022). == Television career ==