Initially Desai started his law practice in Patan, Karad, Satara district. In 1940 he campaigned for election to the District Local Board and was elected president. In 1952 he was elected as the Member of the Legislative Assembly from Patan and was re-elected in 1957. In the same year he became a state cabinet minister. In 1960, Desai was Educational Minister of Maharashtra State. For children of the poor, those whose incomes were not more than Rs.1200/ per annum, he insured that they received an education through Economically Backward Classes facilities. In 1962 he became agriculture minister and in the same year he was asked to take on the responsibility of being the home minister. In 1978–79 he was president of Maharashtra Assembly. He was the main minister in the bilingual state government of Bombay state as well as Maharashtra's government. He played a leading role in the Samyukta Maharashtra Movement and dealt firmly with any outbreaks of violence during their activities in Bombay. In the history of Maharashtra government, Desai is seen as one of strongest home ministers to date. He took steps to make the Home and Police Department strong and reliable. He handled many critical situations during his term as home minister including the outbreak of violence by members of the Saymukta Maharashtra Movement in Bombay. On 11 Dec 1967 a disastrous earthquake took place in Patan. His tireless work to help the people of Maharashtra recover from the disaster was widely appreciated. He came to be known as a true leader of the poor. Journalist Pralhad Keshav Atre called him Loknete. He was elected MLA for his constituency three times and secured a place in the cabinet of the Maharashtra government. He was Speaker of Maharashtra Vidhan Sabha from 4 July 1977 to 14 March 1978.
Cooperative movement
Desai established a sugar factory called Loknete Balasaheb Desai Sahakari Sakhar Karkhana in Patan. This sugar mill was started as a cooperative to provide stability and the opportunity for growth for farmers in the region. Desai worked closely with leading cooperative leaders in Maharashtra such as: Yashwantrao Chavan, Vasantdada Patil, Gulabrao Patil among others.
Shivaji University, Kolhapur
Desai was an educational minister in the first cabinet of Maharashtra government in 1960. He was instrumental in establishing Shivaji University in Kolhapur in 1962. He also established Balasaheb Desai College of Arts and Science in 1969 at Patan.
