Son of Karl David Kircheisen and Friederike Henriette von Lauer. Married (1777) to Karoline Philippine Fischer (d. 1824), with whom he had eight children. Like his father, Kircheisen sought political office, and eventually succeeded to the post of Prussian Minister of Justice (1810-1825).
Friedrich Leopold von Kircheisen began his education at the Köllnisches Gymnasium and Joachimsthalsche Gymnasium, later studying law in Halle. Entering Prussian judicial service, he rapidly rose through the ranks, becoming a Kammergerichtsrat by age 23. Key appointments included director of the Instruktionssenat and vice president of the Kammergerichts (Chamber Court).
Kircheisen was instrumental in developing Prussia's general land law, though his focus lay in criminal justice. Despite declining the prestigious role of Berlin Council President in 1792, he maintained significant influence. In 1795, Kircheisen met Johann Wolfgang von Goethe and began reorganizing the judiciary in the principalities of Ansbach and Bayreuth.
His accomplishments earned him a knighthood and doctorate from the University of Halle, culminating in his appointment as President of the Chamber Court in 1809. From 1810 to 1825, Kircheisen served as Prussia's Minister of Justice during the reform period. Though occasionally at odds with State Chancellor Hardenberg on legal harmonization, Kircheisen's reformist views extended beyond the judiciary.
Beyond his legal work, Kircheisen actively supported social causes. Among other things, he established an endowment fund to aid the needy, and championed the creation of soup kitchens. Friedrich Leopold von Kircheisen passed away in Berlin in 1825 at the age of 75.
Boswell met young Kircheisen when, on July 9, 1764, he took lodgings in the house of the Kircheisen's. His first impression was that young Kircheisen was lively. They saw a lot more of each other for the duration of Boswell's stay in Berlin. On July 26, Boswell and Kircheisen went with C. F. Hübner to the Garden of Corsica.