The Borzya ( from Mongolian "ÃÂþþÃÂö/Boorj") is a river in Zabaykalsky Krai, Russia. The town of Borzya lies along the river. It is a right tributary of the Onon (in Amur's basin). It is long, with a drainage basin of .
In 1918, multiple Communists attempted to destroy the bridge over the Borzya, however, the plan failed due to weather conditions.
The Borzya has its sources in the Kukulbey Mountains. It flows through a wide, swampy valley in a steppe landscape. The river's waters comes mainly from rain, and there are periodic flooding in the summer. The river sometimes dries up completely. The average discharge is .