The accolade recognises individuals whose leadership and commitment to responsible business has resulted in changes and improvements inside their own company and who have inspired other organisations to take action.
Barclays also received the Coffey International Award Example of Excellence, in recognition of its work in Katine, Uganda, supporting community health, education, sanitation and microfinance initiatives.
The award, supported by the UK's Department for International Development, recognises company programmes that demonstrate a positive impact against one or more of the United Nations Millennium Development Goals.
The Katine project was recognised by for extending access to basic financial services to thousands in eastern Uganda and for having "given voice to a community trapped in a vicious cycle of poverty".
The accolades were presented at an event last night marking the Prince of Wales' 25th anniversary as President of Business in the Community.
John's work in supporting homeless people
John has been the Chairman of Business in the Community's Business Action on Homelessness (BAOH) since 2006, a programme which supports more than 5,000 homeless people.
The initiative runs Ready for Work, which is considered as one of the UK's most successful employment schemes for homeless people.
The Prince of Wales said of John's work: "He is someone who has steadfastly campaigned on a single issue with such a forceful and powerful call to action that to demonstrate to others the unique role business can play in society, there can be no better example."
As the Chairman of BAOH, John also leads the annual Prince's Seeing is Believing initiative, visiting hostels and homeless charities.
Under John's leadership, around 225 homeless agencies now refer people to BAOH.
Barclays also plays an active role in supporting unemployed homeless people, offering a number of them opportunities on BAOH work placement schemes in different parts of the Group.
In addition, Barclays colleagues volunteer each year as job coaches.
The Katine project is a joint initiative by Barclays, the UK's Guardian newspaper and non-profit organisation AMREF (African Medical and Research Foundation).
It focuses on identifying innovative ways to provide disadvantaged and remote communities with access to financial services by developing a sustainable microfinance model.
More than 150 Village Savings and Loans Associations have now been established as part of the project, enabling more than 3,200 members of the community to benefit from services such as loans to pay for income-generating activities and savings with interest.
Some of these groups saved as much as USH3.4m (more than £1,000) by the end of their first 52-week savings cycle, with individuals each earning as much as USH300,000 (more than £90) in savings interest.
Barclays has now committed £10m to introduce the microfinance model developed in Katine to 11 countries across Africa, Asia and Latin America, as part of the Banking on Change initiative.
The Katine project also includes socio-economic initiatives providing improved water, sanitation and hygiene practices, improved health and education services, and sustainable economic development.