Cleaning Services Group is banned from trucking in building waste to Pound Bottom, near Redlynch after a planning inspector ruled in favour of the National Park Authority (NPA).
Landowner Hamptworth Estates now has 12 months to remove the dumping facility.
NPA member Leo Randall said: “I am pleased the inspector has recognised the fact that national parks have the highest levels of protection and has ruled that this type of development in this location right next to the open Forest is totally inappropriate.”
An estimated 70,000 cubic metres of rubble, soil and clay was dumped next to the unauthorised landfill site. In November the NPA took action to halt tipping.
An enforcement notice was then issued in December but Cleaning Services Group appealed, although lost.