Lekh Tandon got his break in films partly because his father went to school with Prithviraj Kapoor. So when the young man came to Bombay to try his luck, he stayed with Hindi cinema’s first family, the Kapoors, and started his career as an assistant cameraman on Raj Kapoor’s directorial debut Aag (1947). Lekh Tandon worked with Raj Kapoor and, later, with Kidar Sharma for several years before turning director with Professor (1962). Born in a small town near Lahore, Pakistan, Lekh Tandon moved with his family to India after Partition. His first film was a typical 1960s colour film with Shammi Kapoor shot in the picturesque hills of Darjeeling and featuring Shankar-Jaikishen’s popular music, including the numbers "Aye gulbadan" and "Main chali main chali". Co-starring newcomer Kalpana as the leading lady and Lalita Pawar as the villainous aunt, the film was well received at the box office.

Next, Lekh Tandon helmed the lavish period drama Amrapali (1966) with Vyjayanthimala and Sunil Dutt in the leading roles. The film is remembered for its elaborate war scenes along with Bhanu Athaiya’s costumes, which lent authenticity to the ancient setting. Shankar-Jaikishen once again scored a memorable soundtrack with Lata Mangeshkar singing all the songs. Lekh Tandon later teamed up with Shammi Kapoor and Vyjayanthimala for Prince (1969), which was another major success. The film was written by Abrar Alvi and its songs were extremely popular, especially the Mohammed Rafi song “Badan pe sitare”.

Lekh Tandon's notable film in the 1970s was Rajshri Productions’ Dulhan Wahi Jo Piya Man Bhaye (1977) with Rameshwari and Madan Puri as daughter-in-law and grandfather, respectively, sharing a unique bond. He won the Filmfare Award for Best Screenplay in 1978 for this movie, along with Vrajendra Gaur and Madhusudan Kalelkar. He followed this up with Ek Baar Kaho (1980). Shabana Azmi, who played the lead, would also star in Doosri Dulhan (1983) as a prostitute hired as a surrogate mother by a childless couple, played by Victor Banerjee and Sharmila Tagore.

In Lekh Tandon's romantic melodrama Agar Tum Na Hote (1983), Rekha played a double role alongside Rajesh Khanna and Raj Babbar. The film is best remembered for its title song. Soon after, Lekh Tandon switched gears to direct several successful television serials, including Shah Rukh Khan’s breakthrough roles in Fauji and Circus.

Lekh Tandon is also an occasional actor who made his mark in Swades (2004), Rang De Basanti (2006) and, most recently, Chennai Express (2013), where he played Shah Rukh Khan’s grandfather.