In August 2014, Geraghty was cast as a series regular on the second season of the NBC procedural Chicago P.D., playing Sean Roman. In 2018, Geraghty starred in the TNT drama The Alienist, as NYPD Police Commissioner Theodore Roosevelt.
In August 2014, Geraghty was cast as a main character on the NBC police show Chicago P.D., portraying Sean Roman. In 2018, he starred in the TNT drama The Alienist, playing a high-ranking NYPD officer, Theodore Roosevelt.