Frederick was born in Nuremberg, the second-born son of Burgrave Frederick V and the Wettin princess Elisabeth of Meissen. He entered early into the service of his brother-in-law, the Habsburg duke Albert III of Austria. After Albert's death in 1395, he fought on the side of the Luxembourg king Sigismund of Hungary against invading Ottoman forces. He and his elder brother John, husband of Sigismund's sister Margaret of Bohemia, fought in the 1396 Battle of Nicopolis where they suffered a disastrous defeat. After Frederick returned to Nuremberg, he divided the Franconian inheritance from his father with his brother John, who received the Principality of Bayreuth, while Frederick kept the Principality of Ansbach; the brothers ruled jointly in the Burgraviate of Nuremberg. At first Frederick tried to mediate in the imperial confusion between Sigismund's elder half-brother, the German kingWenceslaus, and the party of Elector Rupert III of the Palatinate, but from September 1399 he fought on the side of Rupert, husband of his sister Elizabeth, nonetheless. Wenceslaus was eventually deposed and Rupert elected King of the Romans on 21 August 1400. Frederick resumed his rule of Ansbach in 1409 and after heavy feuding, entered into the service of King Sigismund. In 1410, the death of Rupert, King of the Germans, left the throne of the Holy Roman Empire vacant. Sigismund enlisted Frederick's help in obtaining the throne. At the time, Jobst of Moravia ruled Brandenburg and thus was one of the prince-electors who had the right to vote for the new king. However, Sigismund disputed Jobst's claim to Brandenburg and his right to vote in the imperial election. Sigismund claimed these rights for himself and designated Frederick to represent him as elector of Brandenburg in the imperial election of 20 September 1410. While Sigismund won this initial vote, Jobst of Moravia won the support of a majority of electors in an election in October 1410 and himself claimed the imperial throne. Jobst's death under suspicious circumstances in January 1411 cleared the way for Sigismund's recovery of Brandenburg and his undisputed election as king of the empire later that year. In gratitude for Frederick's services, King Sigismund made him Oberster Hauptmann and Verwalter der Marken. With an iron hand Frederick fought against the rebellious nobility of the March of Brandenburg and, in the end, restored security. Frederick also became a member of the Parakeet Society and of the League of Constance. At the Council of Constance Sigismund granted Frederick the titles of Margrave and Prince-elector of Brandenburg. On 21 October 1415 the Brandenburg states meeting in a Landtag asked him to rule in Berlin. The king awarded him the formal enfeoffment of the margravate on 18 April 1417. As Frederick did not agree with the forcible action of Sigismund against the Hussites, relations between them cooled. Constant feuding with the nobility of Brandenburg led Frederick to withdraw to his castle at Cadolzburg in 1425 and transfer the regency of the margravate to his son John in 1426. After 1427 he organized the imperial war against the Hussites and subsequently provided substantial assistance in the mediation of the Compacta of Prague at the Council of Basel. Upon his death in 1440, Frederick was succeeded as elector by his second-eldest son, Frederick II.
