Melissa Joan Catherine Hart was born in Smithtown, New York. Melissa's parents' names are Bill William Hart and Paula Hart. She has three sisters, three half-sisters and one brother. Younger sister, Trisha Hart, younger sister, Elizabeth Hart, younger sister, Emily Hart, younger half-sister, Alexandra Hart-Gilliams, younger half-sister, Samantha Hart, younger brother, Brian Hart and younger half-sister, Mackenzie Hart. Most of her siblings have also acted. Melissa's stepfather is Leslie Gilliams, a television executive, and her stepmother is Lisa Hart.
Melissa's career began early on. When she was still a baby, she made her first TV commercial for a bathtub toy called Splashy; soon after, she appeared regularly in commercials - making 25 of them by the age of five. Melissa's fame begin to rise when she auditioned for a Broadway production of The Crucible starring Martin Sheen. This opened the way for her to land the title role in the TV show Clarissa Explains It All. The Nickelodeon series became a big hit and aired for five seasons. The show brought her four consecutive Young Artist Award nominations, of which she won three, and made her a household name among American teenagers. Melissa attended New York University after the show was cancelled, but she did not complete her degree because she resumed her acting career in 1994.
Melissa's fame didn't stop there; she got the lead role for the TV movie Sabrina the Teenage Witch, which eventually led to her also starring as Sabrina in a television series which lasted seven seasons. On July 19, 2003, Melissa married musician Mark Wilkerson, a member of the band Course of Nature. In June 2005, Melissa announced that she and her husband were expecting their first child in January 2006. She gave birth to a baby boy named Mason Walter Wilkerson on Wednesday, January 11, 2006.