The Große Mittweida rises only about 300 m southwest of the summit of the Fichtelberg. After a short course to the west, it turns north and runs parallel to the Zschopau for a longer stretch. After about 11.6 km it joins the Kleine Mittweida. Shortly after the confluence, the Große Mittweida is dammed in the lower basin of the Markersbach pumped storage plant. A large part of the Obermittweida settlement that was previously located at this location was dismantled and flooded from 1969 onwards during the construction of the pumped storage plant. Individual foundation walls can only be seen when the water level is low.
After leaving the dam, the Große Mittweida flows west. On its banks lie the villages of Markersbach, Mittweida, Raschau (all now districts of Raschau-Markersbach), Grünstädtel and Wildenau (both districts of Schwarzenberg/Erzgeb.). After the Schwarzbach and Oswaldbach flow into the latter place, the Große Mittweida flows into the Schwarzwasser.
The lower reaches of the Mittweida were considered part of the Pöhlwasser until the 19th century. Accordingly, it was assumed at the time that the Mittweida flowed into the Pöhlwasser.