Among the savings have been freeing up building space, changes to contracts, improving council tax collection, reducing energy costs, providing services in a different way and improving absence management.
Despite the savings, city leaders warned that more cuts are on the way.
Councillor Phil Wheeler, the city’s finance leader, said: “The fact that we have done so well only means that finding other efficiencies becomes harder.
“There will be difficult choices to make, but with ongoing pressure on public finances we will need to face those.”
City council officials are currently investigating options for sharing services with other authorities and organisations and are looking at the potential to privatise some services.
Since 2006/07, the city council has saved a total of around £117m.