Vidur was the son of Vyas by a Shudra woman. He was a reincarnation of Dharm. When Vichitravirya died childless, Satyavati asked her son Vyas to beget children on the widows of the dead king. Vyas's ugliness prevented Ambalika from visiting him again and in her place, she sent her maid. The child born of this maid was Vidur. Vidur grew up in the palace with Dhritrashtra and Pandu and completed his studies along with them. When he was of marriageable age, Bhishma had him married to the foster daughter of king Devak. Being born of a portion of Dharm, he was wise and was made the minister of the king by Bhishma. He gave good counsel to both, the Kauravs and Pandavs. When Duryodhan was born, there were evil omens and Vidur, in vain, advised Dhritrashtra to abandon him. As the Pandavs were leaving for Varnavat, where Duryodhan had built for them a lac palace, Vidur warned them of the danger that was to come and also sent a man who dug an underground tunnel for their escape. Later, he arranged, in secret, for a boatman to ferry them across the river. Everybody thought that the Pandavs were dead and Bhishma was heart-broken. To ease the latter's pain, Vidur took him into his confidence and related to him their escape. During the Svayamvar of Draupadi, the Pandavs made known their existence and Dhritrashtra, on the counsel of Bhishma, Dron and Vidur, decided to give them half the kingdom. Vidur was sent to Panchal to escort the Pandavs back to Hastinapur. Vidur also carried Dhritrashtra's invitation to the Pandavs for a game of dice, though he did not approve of it.
During the exile of the Pandavs, Kunti stayed at the home of Vidur. The departure of the Pandavs filled Dhritrashtra with fear that the people would rebel against his sons. He summoned Vidur and asked him how he could overcome the problem. Vidur suggested that Dhritrashtra should call back the Pandavs and return to them their half of the kingdom. Dhritrashtra, blinded with love for his son Duryodhan, accused Vidur of being partial to the Pandavs and dismissed him from the palace. The sad Vidur left to join the Pandavs in the forest. Dhritrashtra realised his mistake after sometime and sent Sanjay to fetch Vidur. On his return, Dhritrashtra begged for pardon and Vidur, forgiving his half-brother, continued as his minister. After the thirteen years banishment was over, Vidur counselled Dhritrashtra and Duryodhan to give to the Pandavs the five villages they wanted and avoid the war. During the war, Vidur stayed with Dhritrashtra in Hastinapur. He was immensely heart-broken at Bhishma's death and performed his funeral ceremony. When Dhritrashtra decided to live in the forest, he too joined them and gave himself up to penance. One day, Yudhisthir and his brothers, desiring to meet their elders, went to the forest. Yudhisthir located Vidur who was engaged in penance, subsisting on air alone and with gravel in his mouth. Yudhisthir spoke to him many times, but he received no response. Suddenly a radiance emerged from Vidur and entered the body of Yudhisthir, their union signifying the fact that both were born from a portion of Dharm. Vidur's body fell lifeless on the ground and Yudhisthir proceeded to cremate it, but a celestial voice asked him not to do it.