[3] He grew up in the Williston Park area of Nassau County, New York, where he graduated from Mineola High School in 1964.

He was credited as the producer of the double album of the soundtrack with the progressive rock group Smoke Rise on Paramount Records.

[8] In 1978, Schwartz's next Broadway project was a musical version of Studs Terkel's Working, which he adapted and directed, winning the Drama Desk Award as best director, and for which he contributed four songs.

In the 1980s, Schwartz wrote songs for a one-act musical for children, The Trip, which 20 years later was revised, expanded and produced as Captain Louie.

He then began working in film, collaborating with composer Alan Menken on the scores for the Disney animated features Pocahontas (1995), for which he received two Academy Awards, and The Hunchback of Notre Dame (1996).

A version created for young performers, titled Geppetto & Son, Jr. had its world premiere on July 17, 2009, at the Lyric Theatre in Stuart, Florida.

The American premiere of My Fairytale took place in the summer of 2011 at the PCPA Theatrefest of California and was directed by the composer's son Scott Schwartz.

He has written the theme song for the Playhouse Disney show Johnny and the Sprites, starring John Tartaglia.

On several occasions prior to 2008, Schwartz had reached out to Tim Dang who was the longtime artistic director of Los Angeles-based Asian-Pacific Islander theater company, East West Players (EWP).

In 2008, Applause Theatre and Cinema Books published the first ever Schwartz biography titled Defying Gravity, by Carol de Giere.

Turning to the pop world in 2009, Schwartz collaborated with John Ondrasik in writing two songs on the Five for Fighting album Slice, the title track as well as "Above the Timberline".

"[12] On March 22, 2012, the San Francisco Gay Men's Chorus released "Testimony", composed by Schwartz with lyrics taken from submissions to Dan Savage's It Gets Better Project.

[14] Schwartz returned to write the lyrics for a sequel to Enchanted, titled Disenchanted,[15] and will do the same for a live-action remake of The Hunchback of Notre Dame.

[16] In April 2020 Schwartz participated in a fund-raising video called Saturday Night Seder which featured an "all-star" cast of performers, composers and religious leaders broadcasting from their home computers and cellphones due to the practice of "social distancing" used by people around the world in response to the coronavirus/COVID-19 pandemic.

[3] Although he has not publicly commented on his orientation, as of 2024, Schwartz is in a long-term relationship with Broadway actor and frequent collaborator Michael McCorry Rose.