Sources said the decision to dump the British era .303 rifles was taken after a go-ahead from Chief Minister Akhilesh Yadav.
The chief minister ordered an assessment of the security and weaponry of the force after the June 15 attack on policemen in Firozabad which left two constables dead.
Officials said 2,500 pistols and revolvers have been ordered and will soon be handed to policemen across the state in a phased manner.
Some constables in Lucknow have already been given the new weapons.
Senior Superintendent of Police (SSP) Lucknow, Praveen Kumar, said these light weapons will be used in picket duties, crime detection teams and by constables escorting prisoners.
Guard constables, those on security parameters outside vantage installations and on escort duty of VIPs will be using the AK-47s, the officer said.
The move is being seen as a giant step in protecting the men inkhakhi who have been under attack from criminals in the last one year.
More than two dozen policemen have been shot on duty in the past two years. These include Pratapgarh deputy superintendent of police Zia-ul-Haq who was lynched by an angry mob.