The donation, the single largest one ever received by Unicef from a corporate partner in the UK, will fund projects in countries including India, Egypt, Kenya, Mexico and Russia over the next three years.
The Building Young Futures partnership will aim to provide young disadvantaged people with better access to education, vocational training, employment and opportunities for entrepreneurship. Projects will include mentoring, microfinance and financial training.
Marcus Cox, a director at sustainable development consultancy Agulhas Applied Knowledge, said: "This partnership is an example of how companies are moving beyond traditional corporate philanthropy and beginning to develop new models that help to generate social and economic development, while at the same time building long-term business opportunities."
Marcus Agius, chair of Barclays, said it was vital that business continued to invest in sustainability despite the current economic climate. "Helping to develop and empower individuals and communities is vitally important, and it is fundamental to stimulating global economic growth at the same time," he said.
Building Young Futures is part of Barclays' five-year, £150m community investment programme Banking on Brighter Futures, which supports 1,500 projects around the world.