He was the son of Vyacheslav Yaroslavich, Prince of Smolensk. Following his father"s death in 1057, the child Boris was debarred from his inheritance. Boris was the son of Vyacheslav Yaroslavich, Prince of Smolensk, a younger son of Yaroslav the Wise, Grand Prince of Kiev.
According to the historian Martin Dimnik, Boris was a child when his father died in 1057.
Vsevolod left Chernigov and headed towards Izyaslav, who had set out on a military campaign against Kiev. Boris took advantage of his uncle"s absence and seized control of Chernigov. He only managed to remain in power for eight days and then had to flee to Tmutarakan upon hearing the news of Vsevolod"s return.
Boris and Oleg allied themselves with the Cumans and attacked Vsevolod on the Sozh River, defeating his army in a bloody battle and capturing Chernigov on 25 August 1078.
Boris and Oleg had already left the city by the time Vsevolod and Izyaslav approached it, but the citizens of Chernigov closed the gates and prepared for the siege. The attackers burned the outer parts of the city and wanted to proceed further, but received the news on Oleg and Boris coming to Chernigov"s rescue.
Boris died in a fierce battle "at a place near a village on the meadow of Nezhata" on 3 October, according to the Russian Primary Chronicle.
