Washington was born in New York on December 28, 1942 to Samuel Washington and Kathleen Peterson Erby. She majored in English at the City College of New York, graduating with a bachelor's degree.

After completing college, she worked as a writer, and later as an editor, for several publications, including The New York Post, Essence, Life and Newsweek.

Her one and only novel, Entwined Destines, was published by Dell Publishing in 1980 under the pen name Rosalind Welles as the 575th in its "Candlelight Romance" series of books. The book tells the story of a female African-American magazine reporter who finds true love with an African-American oil executive. The book was described as "the first known romance featuring African-American characters written by an African-American author" in a 2002 issue of Black Issues Book Review. By the time of Washington's death, several imprints were devoted to black romance novels, featuring books by authors such as Rochelle Alers, Beverly Jenkins and Sandra Kitt.

In 1996, the Milwaukee Journal Sentinel called Washington the "mother of the African-American romance", setting the groundwork for a revolution in ethnic romance novels. Washington's book was the first "ethnic romance", a category conceived by Vivian Stevens, an African-American editor at Dell, viewing the book as the first of other such books also aimed at Native American and Chinese Americans. The company published 125,000 copies of Washington's novel, primarily distributed in cities on the East Cost with large African-American populations.

Washington also wrote two works of non-fiction, her 1974 book Sickle Cell Anemia, co-written with Anthony Cerami, and the Uncivil War: The Struggle Between Black Men and Women, published in 1996. A 1998 article she wrote for Essence magazine received notice after she criticized the trend of African Americans who comported to "white standards of beauty" through the use of tinted contact lenses and other techniques.

A resident of Yonkers, New York, Washington died in Manhattan at age 66 on May 5, 2009 due to multiple sclerosis and cancer. She was survived by her parents and a brother.