Rush practiced law in Philadelphia and held public legal appointments, including work as deputy attorney general for Philadelphia County. In the later 1830s he became the city's recorder, remaining in that position until 1841. His correspondence places him among the city's lawyers and officials, alongside his family ties as a son of physician Benjamin Rush and brother of Richard Rush.

During the 1840s he participated in the Choctaw Commission, handling matters connected with claims and the administration of treaties after forced removal. His papers include correspondence with Indian-affairs officials, agents, and lawyers concerned with that process. He also maintained family correspondence and educational interests. In 1851 he prepared diagrams from Euclid for his son William, while invitations to deliver an ode at a cemetery dedication and to lecture to a fire company show that he took part in civic literary activity.

A notebook dated 1859 contains short essays and observations on music, public performers, literature, wealth, wit, and political life. He considered figures such as Lajos Kossuth and the men involved in the Sickles–Key scandal and wrote about Benjamin Rush. These were personal manuscript reflections rather than evidence of a separate career as a published author. Together with his legal and commission correspondence, they preserve his own opinions and working relationships in Philadelphia. He died in 1859; the exact date has not been established here.