The money is part of £330m from dormant bank and building society accounts that will be used to support good causes in the UK over the next four years, Tracey Crouch, minister for sport and civil society said.
The youth employment initiatives will be jointly designed by the Department for Digital, Culture, Media and Sport, the Department for Education and Big Lottery Fund with input from young people and experts across different sectors, including the youth, education, voluntary, community and social enterprise sector, and business sectors. The Big Lottery Fund will set out plans for engagement in the coming months.
Crouch said: "By unlocking millions of pounds from dormant accounts for a range of good causes, we can make a real difference to lives and communities across the country.
"This is part of the government's commitment to building a fairer society and tackling the social injustices that hold people back from achieving their full potential.
"I am grateful to the banks and building societies, as well as Reclaim Fund Ltd, for their work to free up these funds for good causes.
"Working in close partnership with the financial sector and civil society, we are determined to help create a country that works for everyone and build a Britain fit for the future."
Leigh Middleton, chief executive of the National Youth Agency, said the £90m in funding indicates that government is "stepping up its focus on young people".
"It's vital that where you're from or who your family are don't decide your future," he said.
"A fulfilling job plays a key role in providing the stability, security and wellbeing young people need as they navigate the challenges society throws at them.
"NYA is looking forward to supporting DCMS and DfE in engaging with young people to offer the most effective support they can."
Lindsay Levkoff Lynn, interim chief executive of UK Youth, which last year merged with Ambition, said: "Both Ambition and UK Youth have been in conversations with the government for many months about unlocking these funds from dormant bank accounts so we're thrilled at today's announcement to invest £90m to support disadvantaged young people into employment.
"The transition into employment is a tough experience for many young people with almost 800,000 young people currently not in education, employment or training.
"These funds will help our members and the youth sector build on our vital work to empower young people with the skills, confidence and experience needed to feel ready for the work place and build a bright future. We're looking forward to working with DCMS and BLF in developing the initiative over the next few months."
Of the £330m, up to £135m will be used by Big Society Capital to fund stable and long-term accommodation for vulnerable groups such as homeless people and those suffering with mental health issues, as well as to provide support for local charities and social enterprises.
Meanwhile, £55m is set to be awarded to financial inclusion and capability initiatives designed to tackle issues such as problem debt, as well as improving access to financial products and services for those on lower incomes.
And up to £50m will be made available for good causes in Scotland, Wales and Northern Ireland, with each devolved administration deciding how the funds are used.
Accounts are deemed to be "dormant" if there have been no transactions for a period of 15 years.
Since the Dormant Accounts Scheme was established in 2008, almost £1bn of dormant accounts money has been identified. Of this, more than £360m has so far been directed towards good causes across the UK.
The estimation of £330m is based on funds expected to be made available from dormant bank and building society accounts over the next four years under the current dormant account legislation.