Before his accession he had already conducted government business on behalf of his father, Count Philipp III.
The new faith was widely introduced in 1544 and on 28 May 1548, Philipp convened a synod at Bouxwiller with all the pastors of the county of Hanau-Lichtenberg, in order to commit them to the new doctrine.
This apparently happened very hesitantly, and the process of changing the clergy to adherents of the Lutheran faith continued well into the 1560s.
Philipp exchanged the possessions of the secularized Patershausen Abbey for Brumath, which had been held by the Archbishopric of Mainz.
Because Albrecht was only born in the year before his father's death and the fact that there were substantial religious disputes between the guardians, the guardianship could only be terminated in 1608.
The Archbishopric of Mainz objected to the reformation policy of Hanau-Lichtenberg and saw to it that Catholicism prevailed in the condominiums of Ober-Roden and Rodgau.
Philipp IV managed to largely keep his county out of the armed conflicts of the second half of the 16th Century, that were often started under the pretext of religious differences.
He was the first Count of Hanau-Lichtenberg who saw the Alsatian possessions as the most important part of the county, rather than Babenhausen and he moved his residence there.
Philipp IV married on 22 August 1538 in Heiligenberg with Eleonore of Fürstenberg (born: 11 October 1523; died: 23 June 1544).