Riddhi Sen was born into a family deeply rooted in theatre and cinema. His father, Kaushik Sen, is a renowned Bengali actor and director, while his mother, Reshmi Sen, is a dancer. Growing up in Kolkata, he was exposed to theatre at a very young age and became an active member of the theatre group Swapnasandhani. His early performances in stage plays earned him recognition as a prodigious talent.
He made his film debut in Kahaani (2012) and gradually built a reputation with roles in Open Tee Bioscope (2015), Parched (2015), and Nagarkirtan (2017). His portrayal of a transgender woman in Nagarkirtan won him the National Film Award for Best Actor, making him the youngest recipient of the honor. Since then, he has continued to act in Bengali films, Hindi films, and theatre productions, balancing mainstream cinema with socially relevant storytelling.