In 1977, Poonam Dhillon won a beauty pageant that drew attention to her. Legendary filmmaker Yash Chopra then approached Poonam Dhillon in his 1978 film `Trishul`. The popular song Gapoochi Gapoochi Gum Gum from the film was picturised on her and co-star Sachin Pilgaonkar. She was only 16 at the time.

Poonam Dhillon initially refused Yash Chopra`s offer to work in `Trishul`, but the late great producer-director persisted and was eventually able to convince her to be a part of the film under the condition that her filming schedule occurs during her school holidays. `Trishul` (1978), which also starred Sanjeev Kumar, Amitabh Bachchan, Shashi Kapoor, Rakhee, Hema Malini, and Sachin Pilgaonkar was a blockbuster and Poonam Dhillon went on to star in several successful Bollywood films over the years.