The story of the origin of Satyanarayan Vrat and Puja is found in the Skanda Purana. Legend has it that a poor pious man was living in the city of Kashipur. He was an ardent devotee of Vishnu. Seeing His devotee’s utter poverty, Lord Vishnu appeared before him in the guise of a learned man. He then told his devotee about the importance of Satyanarayan Puja and Vrat.
When the pious man performed the Vrata he got rid of his poverty and became rich.
The man continued his worship of Vishnu and attained moksha – liberation from the cycle of birth and death.
After this incident, Satyanarayan Vrat and Puja became famous among people.