[14] On December 14, 2021, it was announced that Sewell would be appointed as the 45th New York City police commissioner by Mayor-Elect Eric Adams.

[18][19][20] On January 1, 2022, Sewell was officially sworn in as first female commissioner of the New York Police Department since it was founded 176 years beforehand.

[4] Sewell was criticized for publicly accepting the appointment in front of a mural of Assata Shakur, convicted of killing a police officer.

[23] While no official reason was given for her resignation, The New York Times reported that she felt frustrated and undermined by City Hall, noting that the Adams administration required its approval for police promotions and handpicked the first deputy commissioner and chief of department.

Her efforts played a leading role in this administration's tireless work to make New York City safer.

"[25] PBA President Pat Lynch stated that Sewell, "took over a police department in crisis and faced tremendous challenges from day one.