His mother, Aniela (née Młynarska), a dancer and writer, was a Roman Catholic native of Warsaw, the daughter of conductor Emil Młynarski.

[7] He made his Broadway acting debut in 1972 and received a Theatre World Award for creating the title role in the musical Pippin, directed by Bob Fosse.

[8] In 2023 Rubenstein starred in the one man biographical show Eisenhower: This Piece of Ground debuting Off-Broadway at the St. Clemens Theatre in New York City and subsequently touring around the US.

[10] Rubinstein's feature films include 21 Grams, Red Dragon,[2] Mercy, Another Stakeout,[2] Someone to Watch Over Me,[2] Daniel,[2] The Boys from Brazil,[2] Rome & Jewel, Jekyll, Kid Cop, Getting Straight,[2] Zachariah,[11] The Trouble with Girls, and The Car.

[16] He also read the part of Captain Kirk in the talking book version of Harlan Ellison's original teleplay for The City on the Edge of Forever.