Actually born with the name Blossom Dearie in the New York Catskills, she began playing piano at an early age and studied classical music before making the switch to jazz while in high school. After graduation, she moved to New York and began appearing with vocal groups like the Blue Flames (attached to Woody Herman) and the Blue Reys (with Alvino Rey). She also played cocktail piano around the city, and moved to Paris in 1952 to form her own group, the Blue Stars of France. Dearie also appeared in a nightclub act with Annie Ross, and made a short, uncredited appearance on King Pleasure's vocalese classic, "Moody's Mood for Love." She recorded an obscure album of piano solos, and in 1954, the Blue Stars hit the national charts with a French version of "Lullaby of Birdland."
After hearing Dearie perform in Paris in 1956, Norman Granz signed her to Verve and she returned to America by the end of the year. Her eponymous debut for Verve featured a set of standards that slanted traditional pop back to its roots in Tin Pan Alley, Broadway, and cabaret. Her focus on intimate readings of standards ("Deed I Do," "Thou Swell") and the relaxed trio setting (bassist Ray Brown and drummer Jo Jones, plus Dearie on piano) drew nods to her cabaret background.
Dearie stuck to her focus on standards and small groups, though her gift for songwriting emerged as well with songs like "Blossom's Blues." She performed in solo settings at supper clubs all over New York, and appeared on the more cultured of the late-'50s New York talk shows. Her husband, flutist Bobby Jaspar, made several appearances on her records, notably 1959's My Gentleman Friend. After a recording break in the early '60s, Blossom Dearie signed to Capitol for one album (1964's May I Come In?), but then recorded sparingly during the rest of the decade.
Finally, in the early '70s, she formed her own Daffodil Records label and began releasing her own work, including 1974's Blossom Dearie Sings and 1976's My New Celebrity Is You. She also performed at Carnegie Hall with Anita O'Day and Joe Williams, billed as the Jazz Singers. She continued to perform and record during the 1980s through to the early 2000s, centered mostly in New York but also a regular attraction in London as well. She retired from playing live in 2006 due to health concerns and died quietly in her Greenwich Village apartment on February 7, 2009.