Born of immigrant parents and raised in a small farming town in New Jersey, Shimerman's family moved to Los Angeles when he was 16 years old. In an effort to help her son meet new people, his mother enrolled him in a drama group and (as the saying goes) the rest is history. Upon graduation from the University of California at Los Angeles, he was chosen as one of eight apprentices out of 900 for the prestigious Old Globe Theater in San Diego. Shimerman appeared prominently in many regional theater productions for the Tyrone Guthrie Theatre, the Mark Taper Forum, the American Shakespeare Festival, the New York Shakespeare Festival, and the Indiana Repertory Theater. Following a move to New York, he landed roles in the Broadway production of Richard Rodger's last musical, "I Remember Mama," "Broadway" with Chris Sarandon and Teri Garr, "St. Joan" with Lynn Redgrave and Joe Papp's production of "Three Penny Opera" with Raul Julia.
Shimerman then returned to his adopted hometown of Los Angeles and his success continued as he appeared in recurring roles in two CBS series. He portrayed Pascal in Beauty & The Beast, and Cousin Bernard in Brooklyn Bridge. He has also guest starred over 65 times on such television series as L.A. Law, Married: With Children, Civil Wars and Seinfeld. Perhaps the most memorable of Shimerman's guest appearances was in Star Trek: The Next Generation when he made his debut as the uncredited Wedding Box in the first season episode entitled "Haven." Later that season, Armin returned to the set of Star Trek: The Next Generation where he portrayed Letek, the first Ferengi in a Star Trek series, in the episode "The Last Outpost."
During the third season hiatus of Star Trek: Deep Space Nine, Shimerman worked on the film "An Eye for an Eye" with Sally Field and Ed Harris. He has also co-starred with Andrew McCarthy, Patsy Kensit and Star Trek: The Next Generation alumna Denise Crosby in the feature film "Dream Man," in which he portrays District Attorney Van Horne.
Teaching his unique Shakespearean acting approach to students throughout Los Angeles keeps Shimerman busy in his spare time. He has taught at the High School of the Performing Arts, the Theatricum Botanicum, the Tyrone Guthrie Theatre, the College of Idaho and several workshop companies, as well as his alma mater, UCLA. He has also spent time as a scribe, writing "The Merchant Prince," as well as two Star Trek novels, "Wheels within Wheels" and "The 34th Rule." Shimerman is active as a National Board Member of the Screen Actors Guild.