Ken was born in Brooklyn to Blanche and George Lerner, the youngest of three sons. Ken attended Brooklyn college where he obtained a BA degree in English. Ken first wanted to be a teacher and was working as one when he was taken by acting by helping his brother Michael learn his lines. The two of them set off for the bright lights of Los Angeles and Ken soon got his first break with a recurring role in Happy Days, in which he ended up playing three different characters.
Since this time he has worked steadily appearing in more than 80 television shows including The Twilight Zone, Columbo, The Golden Girls, Will & Grace, Ally McBeal, ER, Friends and many more, with recurring roles in Beverley Hills 90210, Chicago Hope, Desperate Housewives and of course, Buffy the Vampire Slayer.
As well as continuing to work, Ken has found the time to combine his love of teaching with acting, working initially with his own acting teacher, Roy London until his death in 1993 and now in his own studio, The Ken Lerner Studio which offers free public seminars as well as classes. He is also often called upon by various studios and production companies to give private coaching to their actors.
Ken is father to two children, Sam and Jennifer Lerner who are both also actors.
Ken was not the original Principal Flutie, the role was played by Stephen Tobolowsky in the unaired pilot.