Hundreds of millions of pounds must be pumped into schools to ensure they do not lose out under new funding plans, council bosses have warned.
Schools in England are already facing a squeeze on budgets, and many are set to lose out further under Government plans to introduce a new national funding formula, according to London Councils and Core Cities UK.
The groups represent local authorities in the capital as well as other major cities including Birmingham, Bristol, Cardiff, Glasgow, Leeds, Liverpool, Manchester, Newcastle, Nottingham and Sheffield.
They are calling for an extra £335 million a year to be invested in England's schools to make sure that the new funding formula can be introduced without any schools facing a cut in money.
There are concerns that continued school budget pressures will affect the quality of education children receive, as well as depriving local businesses of skilled employees and in turn damaging the economy, the groups said.
The Government said the new formula will end a "postcode lottery" in school funding.
In a letter to Education Secretary Justine Greening, Judith Blake, leader of Leeds City Council and chair of Core Cities UK, said: "Despite protections on school funding, school spending per pupil has already faced reductions in real terms in many of our schools and the National Audit Office predicts that it is likely to fall by 8% by 2020.
"Our city schools are already dealing with unprecedented rising demand for places, high levels of in-year pupil mobility and increasing challenges around teacher retention and recruitment.
We have very real concerns about how some of our schools will be able to cope with further considerable cuts in funding resulting from the introduction of the national funding formula. Any loss of funding could jeopardise the ability of schools to continue to deliver good educational outcomes and put pupils' longer term employment prospects at risk."
The proposed new national funding formula announced by Ms Greening in December increases money targeted at schools with additional needs, including deprivation.
The changes, introduced from 2018 to 2019, will mean more than 10,000 schools gaining funding, it has been suggested.
However, teaching unions have warned that 98% of schools face a real terms reduction in funding for every pupil over the next few years due to ongoing funding pressures, with an average loss of £339 per primary pupil and £477 for secondary students.
A Department for Education spokeswoman said: "The Government has protected the core schools budget in real terms since 2010, with school funding at its highest level on record at more than £40bn in 2016-17.
"But the system for distributing that funding across the country is unfair, opaque and outdated. We are going to end the historic postcode lottery in school funding and under the proposed national schools funding formula, more than half of England's schools will receive a cash boost.
"London will remain the highest funded part of the country under our proposals, with inner London schools being allocated 30% more funding per pupil than the national average.?
"Significant protections have also been built into the formula so that no school will face a reduction of more than more than 1.5% per pupil per year or 3% per pupil overall. But we recognise that schools are facing cost pressures, which is why we will continue to provide support to help them use their funding in cost effective ways, including improving the way they buy goods and services, so? they get the best possible value."
Shadow education secretary Angela Rayner said: "Schools are facing unprecedented cuts to their budgets and all the Tories have to offer are warms words about how they will help them make the savings.
"When headteachers are faced with the choice of keeping the lights on or letting go of teachers, this is galling to say the very least.
"Children deserve more from this Tory government who have created a school funding crisis, chronic teacher shortages and super-sized classes."