Friedman gained prominence for his role as Frank Vernon in the HBO drama series Succession (2018–2023) for which he won a Screen Actors Guild Award.

[7] In his review for The New York Times, Frank Rich commented "The always impressive Mr. Friedman, as the embittered Wagnerian...allow us to empathize with characters who might otherwise be merely obnoxious or colorless.

[12] On television, Friedman starred as George Silver in Brooklyn Bridge (1991–1993)[13] and has made numerous guest appearances in such series as Miami Vice, NYPD Blue, Without a Trace, and Ghost Whisperer.

Friedman's many feature film credits include Prince of the City (1981),[14] Daniel (1983), The Seventh Sign (1988), Single White Female (1992), and Blink (1993).

The All Movie Guide reviewer wrote, "Avid filmgoers and adherents to the indie film movement that swept through America in the early to mid-'90s will invariably remember Peter Friedman as the sneaky, underhanded, New Age-espousing "self-help guru" who supposedly attempts to offer ailing Julianne Moore a hand up -- but only succeeds in draining her wallet -- in Todd Haynes' harrowing drama Safe (1995).

In truth, that role represented just one of many memorable cinematic contributions for the prolific, highly versatile character actor, whose resumé reads like a best-of list of both independent film and Hollywood product.

[26] For his role as "Frank" in Body Awareness, which ran Off-Broadway in 2008, Friedman received a nomination for the Drama Desk Award, Outstanding Featured Actor in a Play.

[27] The New York Times reviewer wrote: "Mr. Friedman burrows deeply into Ben's anguish at being cut off by the daughter he raised to carry on the family tradition, the wound smarting all the more because he knows his own mistakes have caused the fissure.

[31] Ben Brantley, in his review for The New York Times wrote: "Mr. Friedman brings unblushing good will and vivacity to assignments that include walking around with a clothespin on his nose..."[32] He appeared Off-Broadway in the musical Fly By Night as "Mr McClam" from May to June 2014.

In 2022 he played Lanny Davis in the MeToo movement drama She Said (2022) for which he received favorable notices, with Jocelyn Noveck of The Associated Press describing him as "excellent".

[37] On March 27, 2023, Friedman reprised his role of "Tateh" in a sold-out 25th Anniversary performance of Ragtime at the Minskoff Theater to benefit the Entertainment Community Fund.