Whilst creating the show that was to become Shortland Street, Caterina De Nave set out to pursue many goals, one of which was to have strong powerful women as primary characters to counter stereotype the weak and vulnerable women often portrayed in dramas. De Nave and Television New Zealand also wished for as wide demographics as possible and many measures were set about to ensure the soap would reach a diverse audience. To fulfill this, De Nave created the roles of teenagers such as Nick Harrison, Stuart Neilson and Kirsty Knight to draw in a young audience. Family units were also commonly used in soap operas to sustain a wide variety of demographics in one group of characters and as such, the characters of Nick and Stuart were built around a family unit, with the single mother of Nick's, Jenny, being created to represent single parent families. Jenny was characterized to embody the strong matriarch De Nave wished to portray. Maggie Harper had just started a 4-year course on the natural healing technique, the Feidenkrais method, when she was cast in the role. She was said to bring her own strength and experience to the part. Jenny made her debut on the show's second episode, screened 26 May 1992.

The character of Jenny Harrison was named as a "favourite" to Shortland Street viewers. Harper herself did not enjoy playing Jenny when the soap began, but influenced the characters development with her own personality, she stated, "At first, I thought Jenny was a bit of a victim . They've made her a stronger character now. I got sick of her being so passive. It was annoying to play and I don't think she was a good role model, either." Jenny's abortion in 1995 was seen as highly controversial and several complaints were made to the Broadcasting Standards Authority, though none were upheld. A storyline featuring Jenny developing a cyst was introduced to the soap but never continued due to the Writers effectively forgetting about it. This later became a codename, "Jenny's cyst", for forgotten or misplaced storylines occurring in the soap. 2011 advertisements for repeats of the soap's original episodes, noted Jenny as one of the featured characters to entice an audience.

As the nineties progressed, Harper maintained her role and by 1996, was one of only three remaining cast members of the original 16, alongside screen son, Karl Burnett (Nick Harrison) and Angela Dotchin (Kirsty Knight). Dotchin departed two years later, leaving only the Harrison family as the remaining original cast. Several months later, Harper quit the role after falling in love with a man she met at a fancy dress party. Harper was pleased to be in a relationship upon leaving the show due to Jenny's constant thoroughfare of poor romances. The character of Jenny's best friend, Marj Brasch (Elizabeth McRae) was reintroduced to the soap in her final episodes as a means of writing her out. Shortly after quitting Harper realized the extent of how happy she was, stating, "The week I finished I was on my bike cycling away and I thought, 'Oh, I have no lines to learn, how wonderful'." Following Jenny's departure in August 1998, only one original cast member remained on the show, being that of her son Nick. Harper reprised the role in 2002 for her onscreen son's wedding.

Jenny was created as the single mother of teenage rebel, Nick Harrison (Karl Burnett) after surviving an abusive marriage with Nick's father. The personal assistant to the Shortland Street clinic's Chief Executive Officer, Michael McKenna (Paul Gittins), Jenny was the embodiment of the strong and wise matriarch the shows producers wished to portray. Jenny headlined numerous storylines including a secret love affair with Guy Warner (Craig Parker), a secret revealing Nick may not be her biological son, numerous romances, a pregnancy and later abortion, breast cancer, a brief marriage to the villainous Ian Seymour (David Press) and departing the show to work in politics alongside best friend, Marj Brasch (Elizabeth McRae). By the time Jenny departed in 1998, she was the shows longest running character and only one of the two remaining original cast, beside her son Nick.