Landestheater Niederösterreich, State protected theater in St. Pölten, Austria.

The Landestheater Niederösterreich is a heritage-protected theater building in St. Pölten with a resident ensemble that stages productions on a main stage and in a workshop theater. These venues accommodate different types of stagings, from large productions to experimental works.

In 1820 master builder Josef Schwerdtfeger converted a military prison on today's Rathausplatz into St. Pölten's first permanent theatre, opened on 26 December 1820 with a dance event; the first play followed a day later. After the Ringtheater fire of 1881 the house closed for lack of fire safety and served only as a ballroom. Heinrich Wohlmeyer's 1893 rebuild kept just the outer walls and gave the reopened Stadttheater an enlarged stage, an enlarged orchestra room and 500 seats.

The theater regularly features works by Austrian dramatists and invites artists to explore new productions. Its programming reflects regional artistic traditions while blending them with contemporary stagings.

The theatre stands on Rathausplatz, the square it has occupied since 1820, when a converted military prison opened there as St. Pölten's first permanent stage. The main house and the Theaterwerkstatt, a second venue with 120 seats added in 2002, host the spoken-theatre programme; the foyer and theatre café were redesigned in summer 2012.

The building was used as SS quarters and storage during the Second World War and was damaged by bombs, losing its roof. When it reopened in 1948 it still had no roof, so performances were held in the open air until the roof was restored.