The House and Merit Order of Duke Peter Frederick Louis (German: Haus und Verdienstorden von Herzog Peter Friedrich Ludwig) or proper German Oldenburg House and Merit Order of Duke Peter Frederick Louis (German: Oldenburgischer Haus- und Verdienstorden des Herzogs Peter Friedrich Ludwig) was a civil and military order of the Grand Duchy of Oldenburg, a member state of the German Empire.

The cross had a blue enameled center medallion with the crowned monogram of the Peter Frederick Louis in gold.

Each arm on the reverse carried dates written in a cursive script: "17 Jan. 1775", "6 Juli 1785", "21 Mai 1829", and "27 Nov. 1838".

A special chapter of the order, the capitular knights, open only to Oldenburgers, had a badge which consisted of the medallion, surrounded by a green enameled wreath of oak leaves.

In October 1918, an additional provision was made for a war decoration of a wreath of laurels affixed to the badge and breast star.