One of Einstein's earliest industry jobs was writing for "The Smothers Brothers Comedy Hour" (1967-1970) for which he and the other up-and-coming writers (including Rob Reiner, Steve Martin and McLean Stevenson) earned an Emmy. He also created the character of "Officer Judy" on the show, among others. After CBS pulled the controversial Smothers Brothers off the air, Einstein continued to create wild characters on a string of other varety shows, including "The Sonny and Cher Comedy Hour" and "Van Dyke and Company" (1975) and a series of specials starring singer/dancer Lola Falana. He also frequently appeared on the "The Tonight Show" with Johnny Carson and both of David Letterman's late night talk shows.

Einstein's best known character is Super Dave Osborne, the greatest stuntman ever. Super Dave, introduced in 1977 on the Einstein-produced "Redd Foxx Show," first gained popularity on John Byner's "Bizarre" (Showtime from 1980-1985) and ultimately led to a string of television series and specials built around the character, most notably the late night series "Super Dave" (Showtime, 1987-1993) and the feature film "The Extreme Adventures of Super Dave" (2000), which he wrote, produced and starred in. Before that, Einstein wrote, produced and directed the cofeature comedy "Another Nice Mess" (1972) and appered as a sporting goods salesman in his brother's film "Modern Romance" (1981). Post-Super Dave, Einstein managed to connect with a new wave of comedy innovators, appearing in the Harry Shearer-directed comedy "Teddy Bears' Picnic" (2002), frequently lending his voice to Comedy Central's puppet crank-calling series "Crank Yankers," enjoying a recurring role as Larry David's frequent nemesis Marty Funkhouser, and appearing on "Arrested Development" as the surrogate presence for the imprisoned George Bluth, Sr. (Jeffrey Tambour).