He continued being a councillor for East Ham Central until 2018 when he stood down to focus on his London Assembly work.

In May 2016, Desai was elected to the London Assembly succeeding John Biggs as the member for City and East, winning nearly 58% of the vote.

[6] During his time on the Assembly, he has campaigned on issues including police pay[7] and conditions,[8] anti-fascism,[9] and hate crime at football grounds.

[10][11] In 2022, Desai successfully called for a Metropolitan Police investigation into breaches of Covid regulations at Downing Street under the Boris Johnson administration.

[22] On 7 January 2025, Desai was administratively suspended by the Labour Party following an arrest and police investigation in connection with what is understood to be a serious allegation against him.