Josh Radnor was born in Columbus, Ohio, to Carol Radnor, a high school guidance counselor, and Alan Radnor, a medical malpractice lawyer. He has two sisters, Melanie Radnor and Joanna Radnor Vilensky.
Radnor spent his childhood in Bexley, Ohio, a small city nestled within Columbus. He attended Orthodox Jewish day schools, including the Columbus Torah Academy, and was raised in Conservative Judaism.
Radnor's high school years were spent at Bexley High School, where he later went on to attend Kenyon College. At Kenyon, Radnor's school's theater department honored him with the Paul Newman Award.
During his time at Kenyon, Radnor took a semester-long acting course at the National Theater Institute at the Eugene O'Neill Theater Center in Waterford, Connecticut. He graduated from Kenyon College in 1996 with a Bachelor of Arts degree in Drama.
Radnor furthered his education by earning a Master of Fine Arts degree in acting from New York University's Graduate Acting Program at the Tisch School of the Arts in 1999.
In addition to his academic pursuits, Radnor participated in an Israel experience program in Tzfat with Livnot U'Lehibanot in 1997.
