Desai enrolled as an advocate on 30 July 1973, and began practicing law, working in the chambers of S.C. Pratap before he was appointed as judge in the Bombay High Court, as well as with her father, S.G. Samant, who practiced criminal law. In 1979, Desai began working as a Assistant Government Pleader in the Bombay High Court, appearing for the Government of Maharashtra, and in 1983, was appointed as an Assistant Government Pleader and Additional Public Prosecutor for the State of Maharashtra. In 1986, Desai was appointed as the State of Maharashtra's Special Public Prosecutor in cases concerning preventive detention. In 1995, she began appearing for the Government of Maharashtra as a government pleader in appeals at the Bombay High Court.
Desai was initially appointed as an additional judge at the Bombay High Court on April 15, 1996 for a period of two years, and was confirmed as a permanent judge on 12 April 1998. She continued to serve as a judge on the Bombay High Court until she was appointed to the Supreme Court in 2011.
Judge, Supreme Court of India (2011-2014)
On 13 September 2011, Desai was appointed as a judge at the Supreme Court of India and served in that capacity until 2014. She was the fifth woman to be appointed as an Indian Supreme Court judge.
Desai took charge as chairperson of Appellate Tribunal for Electricity on December 1, 2014 in New Delhi and continued to serve in that capacity until 29 October 2019.
Chairperson, Advance Ruling Authority Income Tax (2018-2019)
Desai was appointed as Chairperson of the Advance Ruling Authority in 2018 and held the position until 29 October 2019.
On 28 September 2018, the Government of India constituted a Search committee of eight, chaired by Desai, under the Lokpal and Lokayuktas Act, 2013, to search for and recommend a Chairperson and members for India's anti-corruption ombudsman agency, the Lokpal. The Committee provided its recommendations to the Selection Committee on 28 February 2020.
Desai was appointed as the Head of the Delimitation Commission of India on 13 March 2020.
Jurisprudence
On 8 May 2012, the Supreme Court benchcomposed of Ranjana Desai and Altamas Kabir ordered the government to end the Haj subsidy by 2022. On 27 September 2013, in a landmark judgement, a three-judge bench consisting of the Chief JusticeP Sathasivam and Justice Ranjana Prakash Desai and Justice Ranjan Gogoi of the Supreme Court of India ruled that the right to register a "none of the above" vote in elections should apply. The court said that Negative voting would lead to systemic change in polls and political parties will be forced to project clean candidates. The Election Commission has said that the judgement will be implemented immediately.
