The foundation was established last year by the world's fourth richest football club, which has annual revenue of £168m, according to Deloitte's Football Money League. It will operate three-year partnerships with two national and four local charities.
It won't give grants, but aims to help partners raise a total of £1m over three years by providing help with signed merchandise and free facilities. Macmillan Cancer Support, the Children's Society and Legacy Rainbow House are among those hoping to be selected.
"The winning charities will receive all the benefits of being associated with the Manchester United brand," said Trish Hirst, chief executive of the foundation.
In January, Tottenham Hostspur, which is listed by Deloitte as the world's 15th-richest football club and has a revenue of £74.1m, put £4.5m into its foundation.