Born to a Pennsylvania mining engineer, Allyn Joslyn embarked on his theatrical journey at the tender age of 17, marking the beginning of a illustrious career that would soon find him gracing the stages of Broadway with increasing frequency. His foray into the world of Hollywood filmmaking commenced in 1936, with a debut appearance in the 1937 cinematic release, They Won't Forget. Joslyn's on-screen presence was characterized by a nervous, at times dyspeptic demeanor, which proved to be an uncanny fit for the portrayal of pompous, wealthy snobs that had become a staple of his acting repertoire.
Throughout his professional life, Joslyn remained an extremely prolific radio actor, lending his talents to over 3,000 separate shows, cementing his status as a versatile and sought-after performer in the world of audio drama.