Sadhana was born on 2nd Sept 1941 in Karachi, Sind (part of Pakistan since 1947). She was the only child of Shivdasanis, a Sindhi Family. Her mother schooled her at home till her 8 year of age. They fled to Mumbai after the partition of India in 1947.
She was a part of a song in Raj Kapoor's "Shree 420" in 1955. She played a second lead in a Sindhi film called Abana (1958), which got her noticed and entry to an acting school. The school was run by film producer Sashadhar Mukherjee, and also had another aspiring actress named Asha Parekh as a student.
In Love in Simla (1960), Mukherjee gave his director, R.K. Nayyar (Raj Kapoor's assistant) a say in who should play the heroine from his school. Nayyar chose Sadhana, and she was paired with Mukherjee's son Joy Mukherjee in the film. During the making of the film, Sadhana and director R.K. Nayyar fell in love, and married in 1965.
R.K. Nayyar asked Sadhana to style her hair with a fringe (like Audrey Hepburn). This hairstyle later became a craze and is still referred to as the famous "Sadhana cut".