Sooknanan Bachelor of Science, summa cum laude, from St. Francis College in 2002, a Master of Business Administration with distinction from Hofstra University in 2003 and a Juris Doctor summa cum laude, from Brooklyn Law School in 2010.

From 2012 to 2013, she worked at the United States Department of Justice as an appellate attorney in the Civil Division.

Before her resignation, The New York Times reported that she denounced the firm's work in Pennsylvania on behalf of the Trump administration, saying that one lawsuit "was brought for no other reason than to deprive poor people of the right to vote.

From 2023 to 2025, she served as the principal deputy assistant attorney general in the Civil Rights Division of the U.S. Department of Justice.

President Biden nominated Sooknanan to the seat vacated by Judge Florence Y. Pan, who was elevated to the United States Court of Appeals for the District of Columbia Circuit on September 28, 2022.