The 1998 series is based on Jill Murphy's book series of the same name, adapting the first two novels (The Worst Witch and The Worst Witch Strikes Again) in its first series before moving to original stories.

The show spawned a franchise including two follow-up series, Weirdsister College and The New Worst Witch, the latter following Mildred's younger cousin Hettie at the same academy.

Felicity Jones played Ethel Hallow in Series 1 but was replaced by Katy Allen for Series 2 and 3.

Terrence Hardiman played Grand Wizard Egbert Hellibore but was replaced by Richard Durden for Series 2, with Hardiman returning for Series 3.

Clare Coulter, who played Headmistress Miss Cackle, is the only actor from the original 1998 series who returned to reprise her role in the spin-off The New Worst Witch.

Kate Duchêne, who played the fearsome Miss Hardbroom, was replaced by Caroline O'Neill when the character continued in The New Worst Witch.

The series was nominated by the Royal Television Society for Best Children's Drama in 1999.

Lead actress Georgina Sherrington won the Young Artist Award for Best Performance in a TV Comedy Series – Leading Young Actress in 2000.