Jessica is portrayed as a determined, independent young woman, who experiences an oppressed homelife living with Shylock and eventually elopes with a penniless Christian named Lorenzo. Before Jessica leaves her father's home, she steals his valuable jewels and money and expresses her desire to become a Christian. Jessica's romance with Lorenzo is an important subplot in the play, and some critics speculate that her actions push Shylock over the edge by motivating him to extract a pound of flesh from Antonio. In act 2, scene 6, Jessica disguises herself as a boy and elopes with Lorenzo under the cover of darkness. Her disguise mirrors Portia and Nerissa's costumes later in the play when they save Antonio in a Venetian court of law.

In act 3, scene 5, Shylock's friend Tubal informs him that Jessica has been frivolously spending his money in Genoa and even traded a priceless turquoise ring for a monkey. Shylock is infuriated by Tubal's report and vows to extract a pound of flesh from his enemy. Jessica and Lorenzo proceed to travel to Belmont, where Portia puts them in charge of her estate while she and Nerissa travel to Venice to save Antonio. In act 3, scene 5, Launcelot teases Jessica about her genealogy, but she is able to match his wits. By the end of the play, Jessica's prospects seem fortunate as she and Lorenzo will inherit the remainder of Shylock's wealth when he dies and the stigma of being a Jew has been eliminated as a result of her conversion.