Plans to turn Walkley Library into a shared venue featuring a café bar have been given the go-ahead.
Councillors approved proposals to revamp the building, on South Road, at a planning committee meeting on Tuesday.
They agreed to a condition restricting opening hours to 11.30pm from Monday to Thursday, and on Sundays.
But the committee said the café bar could open until 1am on Fridays, Saturdays and the Sundays before a Bank Holiday.
The library has been led by volunteers since 2014, when Sheffield Council handed over control following budget cuts.
Under the new arrangement, book loans will continue alongside the café, which is set to be run by the True North Brew Co - formerly the Forum Group.
The proposal involves putting up a two-storey extension behind the main building, to provide a kitchen, staff facilities and toilets.
An area towards the front of the building facing South Road, currently the children’s book section, will be kept as the library.