This is the most ambitious shared service project currently being taken forward in the UK and, as such, comes with significant risks, said the council in its business plan.
Staff numbers under the new shared services model are expected to decrease by around 25% over time, which could see more than 100 IT roles go. IT is the most expensive function across the councils with a total cost of £58m per year.
"This will need to happen with or without shared services. "Taking the shared services approach, we expect that these reductions should be achieved by natural change and voluntary redundancy," said the councils in a joint statement.
Some of the cost-cutting measures will include more services going online, managers having to "self serve" and new IT skills being required. Service levels could dip during transitions, it warned.
An investment of between £28m and £31m over the first five years will also be required to realise these savings.
The participating councils include Glasgow, Inverclyde, East Renfrewshire, Renfrewshire, East Dunbartonshire, West Dunbartonshire, and North Lanarkshire.