The district was created 18 February 1818 as the Landkommisariat Pirmasens. During the communal reforms of 1968-72 several changes were made to the district. In 1969 the neighboring district Bad Bergzabern was dissolved and some part of it was added, while other municipalities were incorporated into the city Pirmasens. In 1972 the district Landkreis Zweibrücken was dissolved and added into the district Landkreis Pirmasens, which on 1 January 1997 renamed itself to Südwestpfalz.
The three red bars on golden ground in the left half is the coat of arms of Hanau-Lichtenberg, while the lion in the right half is the lion of the Electorate of the Palatinate. These mark the two historic states which were located on the district's area until the end of the 18th century.