The Warndt (French pronunciation: [vaʁnt]) is an extensive forest area of approximately 5,000 hectares (19 sq mi) including parts of the German Saarland and the French region Grand Est west of Saarbrücken.

The geology of the Warndt is composed of Buntsandstein permeated by veins of iron ore and deposits of hard coal.

The area is bounded by the Saar and two of its left tributaries, the Bist in the north and the Rossel in the south.

Off-limits to the general population, the Warndt had been a lordly hunting ground since the Middle Ages.

Their settlements in the Warndt, in Ludweiler, caused a lasting effect on the area, since they brought the craft of glassblowing and introduced the glass industry to the Saar.