Lvov began his career as a deputy governor of Nizhny Novgorod (1610), Rylsk (1615), and Astrakhan (1618–20).
In 1634, Lvov was one of two heads of Russian delegation in Russo-Polish negotiations which resulted in signing the Treaty of Polyanovka.
After this success he was sent to Poland in 1635 as a head of an embassy to witness Władysław IV Vasa's oath of "eternal peace".
In 1644, Lvov and Boris Morozov became main opponents of Tsar Mikhail's plan to marry his daughter Irina to Dutch prince Valdemar Christian (they feared this marriage would generate an independent center of power).
In January 1626, Lvov was appointed to serve as a majordomo of the Tsar's court, in 1627 was made an okolnichy and official head of the Prikaz Bolshogo Dvortsa ('Prikaz of the Great Palace'), a government office dealing with the Tsar's palace economy and judging monasteries.