Marshall was born on September 30, 1929, in Bronx, New York City. She graduated with a B.A. in education from CUNY Queens College. She was a teacher for eight years.
In 1969, she left teaching to become the first Director of the Langston Hughes Library in Queens. She was married to Donald Marshall until his death; they had two children, Donald Jr. and Agnes Marie. She entered politics as a Democrat.
She was a member of the New York State Assembly for eight years and a member of the New York City Council for ten.
She was elected as Borough President of Queens in November 2001, to succeed the term-limited Claire Shulman. As Borough President, Marshall made marketing Queens as a tourist destination one of her priorities. In 2005, she won a second term, defeating her Republican/Conservative challenger Philip T. Sica with 75% of the vote to his 25%. She was inaugurated to her second term as President of the Borough of Queens on January 3, 2006 in a ceremony held at Terrace on the Park in Flushing Meadows Corona Park. Marshall outlined her plans for the next four years including health care, education, housing and new park projects.
In November 2009, Marshall was re-elected to a third term.
Marshall died on March 4, 2017 at her home in California, aged 87. A widow, she was survived by her two children.
New York City’s Mayor Bill de Blasio said in a statement:
“Helen Marshall was as bighearted, dynamic and brave as the borough of Queens, which she represented with such determined grace for three decades in many roles, including as its first African American Borough President. New York City will miss her deeply, but her memory will live forever in the libraries, schools, and neighborhoods she uplifted and in the many hearts she touched. My deepest condolences to her family, friends and all who knew her.”