Orkdalen or Orkladalen (English: the valley of Orkla) is a traditional Norwegian district in Sør-Trøndelag county, Norway. In the early Viking Age, before Harald Fairhair, Orkdalen was also a petty kingdom.
The district encompasses the valley municipalities that surround the Orkla River. The municipalities in the district are Rennebu, Meldal, and Orkdal. The municipalities of Oppdal and Skaun are often traditionally counted as a parts of the district also even though they lie outside the actual Orkla River valley. The river itself actually begins in Oppdal and then winds its way north to the Trondheimsfjord.