The principal, best known as simply Principal, is a minor character in the books. Like Mrs., his first and last name are unknown. He wears glasses and is described by Junie B. as a "baldy man", much to his dismay. He is the main headmaster at the school. In the kindergarten books Junie B. got sent to his office a lot, but in first grade books she isn't. In Junie B. Jones & the Stupid Smelly Bus, he sternly scolds Junie B. for hiding in the closet and not getting on the bus. Principal also seems to has a sense of humor, He points this out in the last kindergarten book after she was sent over for an inappropriate poem about smelly feet. He is very stern about Junie B. but believes she has potential in improving.

Principal is described to be a nice person but he's strict and impatient. He has a woman in his office described by Junie B. as "the grouchy typing lady". He is seen less often in her first grader novels although he is still the current principal.