The decision was taken late on Tuesday night at a virtual cabinet meeting chaired by Chief Minister Yogi Adityanath, who last week tested positive for the virus.
Adityanath tweeted: "In the cabinet meeting it has been decided that coronavirus vaccination of all the people above 18 years of age in Uttar Pradesh will be made free... Coronavirus will lose, India will win."
The health department has been tasked with working out the logistics of this exercise in the most populous state in the country.
"We have to increase vaccination centres and create a database of the target age group," the chief minister said in a statement.
On Monday, the central government had said that all those over the age of 18 can get the shot from May 1.
Currently, only people over 45 are eligible.
Faced with criticism over reports of vaccine shortage, the centre had also said that states could now buy doses directly from manufacturers - up to 50 per cent of their supply - at a 'pre-agreed price'.
Uttar Pradesh is India's second most affected state, with over two lakh active coronavirus cases. New cases have seen a frightening spike since March 31, when 918 cases were reported.
On Tuesday, nearly 30,000 new cases were detected.
The deadly surge in new cases has increased pressure on the state's already creaking health infrastructure, with hospital beds unavailable even in the bigger cities. Another point of concern is the supply of medical oxygen.