Nair was called to the Singapore Bar in 1992. Nair was appointed as the deputy attorney-general (DAG) for a three-year term starting on 1 March 2017, followed by another three-year term commencing on 1 March 2020. He has since resigned as a member of the
People's Action Party as well as the director of Drew & Napier. He was the first ex-lawmaker in Singapore to take on the role of a public prosecutor. and
Tan Cheng Bock's constitutional challenge to the
elected presidency in 2017. Nair, in his capacity as the DAG representing the government, was criticised by Tan for his comments in the High Court. Nair was quoted to have said that Tan's motives "are purely selfish and he has shown no regard for the principle of multiracial representation which Parliament intended to safeguard". In November 2017, Nair appeared before the Court of Appeal to argue against the acquittal of Mohd Ariffan Mohd Hassan, who was accused of raping his lover's daughter. The court upheld Mohd Hassan's acquittal and dismissed the appeal, issuing a landmark judgment setting out the criteria for bringing in fresh evidence applying to the prosecution. In June 2018, Nair successfully argued the prosecution's appeal for the
death penalty to be imposed on
Chia Kee Chen, who murdered his wife's ex-lover
Dexmon Chua. In 2019, Nair led the prosecution team during the trial of
Leslie Khoo Kwee Hock, who strangled his girlfriend Cui Yajie near
Gardens by the Bay and burned her body in what was known as the "
Gardens by the Bay murder" case. Khoo was subsequently convicted of murder in July 2019, and the prosecution argued for him to be sentenced to
life imprisonment, on the account that his actions did not warrant capital punishment since he did not exhibit any viciousness or blatant disregard for human life. The judge agreed, and imposed a life sentence on 19 August 2019. Khoo appealed against his conviction and sentence, but later withdrew it. Nair also acted for the prosecution in the appeal hearing of
Roshdi Abdullah Altway, a drug trafficker who was sentenced to death in 2020 despite his defence of safekeeping the drugs and not for the purpose of trafficking. Roshdi was previously sentenced to hang in 1994 for murdering a
Central Narcotics Bureau inspector before he escaped the gallows and re-sentenced to ten years' jail upon an appeal. Roshdi was eventually hanged on 10 April 2025 after losing his appeals. In September 2020, Nair was appointed to conduct a prosecutorial review for a
wrongful conviction case of a domestic worker,
Parti Liyani, who was wrongfully accused of theft. Nair begun serving as a Judge in the High Court from January 2, 2023, following his appointment by President
Halimah Yacob ==Political career==