The Delger mörön (Mongolian: Дэлгэр мөрөн, lit. wide river) is a river in the Khövsgöl aimag in northern Mongolia. It rises in the Ulaan Taiga range close to the Russian border. It is 445 kilometres long, and has a drainage basin of 26,600 square kilometres.
Together with the Ider River, it is the headwaters of the Selenge River. It meets with the Ider at Tömörbulag, thereafter becoming the Selenge.
The Delger mörön is frozen for 128–175 days through the year. There is a ferry in Bayanzürkh, and a concrete bridge just south of Mörön.
