With her close friend Marsha P. Johnson, Rivera co-founded the Street Transvestite Action Revolutionaries (STAR), a group dedicated to helping homeless young drag queens and trans women of colour.
Sylvia was born in New York and raised by her mother until she was three. Her mother then committed suicide and Sylvia was looked after by her Venezuelan grandmother. At just eleven, Sylvia began living on the streets, after her grandmother had showed a distaste for her decision to wear makeup. She was taken in by the local drag community, who named her Sylvia.
Her activism began during the African-American Civil Rights Movement (1955–68) and continued through the anti-war movement during the Vietnam war (mid-1960s) and second-wave feminist movements (mid-1960s). She stated that she was a patron of the Stonewall Inn and present during the Stonewall Riots in 1969. However, some Stonewall historians, including David Carter, questioned these claims based on contradictory statements made by Sylvia – as well as testimonies relayed to him by early gay rights activists, including Marsha P. Johnson who denied she was present.
She also actively advocated for the homeless and those with substance abuse issues.
In early July 1992, shortly after the 1992 New York City Pride March, Rivera’s close friend Marsha P. Johnson was found dead floating in the Hudson River. Police promptly ruled Johnson’s death a suicide Sylvia and other supporters of Marsha were outraged and insisted Marsha had not been suicidal. Three years later, Sylvia tried to commit suicide by walking into the same river.
In the final five years of her life, Sylvia became more politically active and gave speeches relating to Stonewall and how the LGBT community need to unite and fight for their history. In 2001, she resurrected STAR (changing the ‘T’ from transvestite to trangender) and fought for the New York Transgender Rights Bill. She also attacked the human rights campaign for standing in the way of trans rights. She passed away in 2005 from liver complications.