Figures released for the first time show 398 fortunes worth almost £2.5 million are currently handled by the authority.
Such corporate appointeeships have proven controversial in the past after campaigners raised conflict of interest concerns over care providers also acting as financial guardians.
“With regards to local authorities acting as corporate appointee they should very much be the last resort if no family members or close friends can be found to undertake the tasks and responsibilities of the role,” said Sean Tyrer, chief executive of the Money Carer Foundation.
“The individual must of course be willing and suitable to assume the appointeeship.”
The Evening News obtained the figures under Freedom of Information laws after the council became embroiled in a high-profile row over the estate of former actor Howard “Lew” Lewis.
Family of the former Maid Marian star accused the authority of “robbing” him of his £325,000 fortune – but the council maintained it was acting in his best wishes.
Daughter Debbie Milazzo, 42, said: “A number of people have contacted me. It seems to be a big issue with lots of people with elderly relatives not giving their consent.”
Lovable character actor Lew was most famous for playing Rabies in the award-winning 1989 BBC children’s television comedy series Maid Marian and Her Merry Men.
Stars including Blackadder’s Tony Robinson paid tribute to him after he died, aged 76, in January.
Mr Tyrer claimed conflicts of interest were potentially posed when local authorities acted as corporate appointees.
“Yes there are concerns,” he said. “Particularly when a local authority takes on the role of the appointee and at the same time is financially assessing how much a person should be paying the local authority towards the cost of their care provided by that local authority.
“It is a fact that local authorities do not have a statutory responsibility to take on this role and many are realising that it is clearly not best practice that they do so going forward.”
Many councils are now opting to refer appointeeships to independent services such as The Money Carer Foundation, said Mr Tyrer.
The Cheshire-based social enterprise was selected this year to be part of a Westminster Parliamentary Review to represent best practice and innovation over finances.
Typically, people with mental health issues, including dementia, living in care homes and incapable of managing their own finances are subject to appointeeships.
The appointee is preferably family or friends over the age of 18, a trusted organisation or local authority to manage the individuals funds and any benefits they may be entitled to.
Nominated officers authorise applications to the city council for corporate appointee accounts and administer funds. The process is independent of court scrutiny.
Funds are allocated and released according to the individual’s particular needs – with cash covering care costs and day-to-day personal expenses.
A Council spokeswoman said: “Local authorities and other bodies take on corporate appointee accounts to manage the finances and welfare of individuals in their care.”