Gurdial Singh Dhillon was elected to the fourth Lok Sabha in 1967 on a Congress ticket from the Taran Taran parliamentary constituency in Punjab.

Following the resignation of the then Speaker Neelam Sanjiva Reddy to contest the presidential election. Dhillon was unanimously elected Speaker on August 8, 1969. Dhillon had the distinction of being the youngest Speaker of the Lok Sabha till then. After he was returned to the Lok Sabha in 1971, Dhillon was re-elected Speaker on March 22, 1971.

Dhillon resigned as Speaker on December 1, 1975 and was sworn in the same day as the minister of shipping and transport in the Union Cabinet.