Councillors, residents, members of the armed forces and representatives from different countries banded together for a flag-raising ceremony at Guildhall Square.
The celebration was one of many across the country and in other Commonwealth countries across the world, to promote inclusiveness and diversity, while uniting a family of nations for tolerance and peace.
Marie Costa, chairwoman of the African Women’s Forum in Portsmouth, and who represents Nigeria, was asked to speak at the event.
She said: ‘The Commonwealth is a community of nations that brings together people from diverse backgrounds for the good of the world.
‘In Portsmouth we have a very diverse community of people and celebrating an initiative like this can bring all different kinds together.’
Marie has lived in Portsmouth since 1969.
She added: ‘We have to celebrate all that is good in the world because there’s so much strife and fighting, that Commonwealth Day can encourage us all to be better.
‘We need to share values of peace, support, and partnership for the good of the community.’
Fifty-two countries are members of The Commonwealth spanning Africa, Asia, America, Europe and the Pacific.
The event was attended by the Lord Mayor and Lady Mayoress of Portsmouth, David Fuller and Leza Tremorin, serving members of the Royal Navy, and more.
Cllr David Fuller read the Commonwealth Affirmation and confirmed the community’s commitment to upholding the values set out in the Commonwealth Charter.
He spoke of an international commitment to ‘serve one another in a spirit of respect and understanding’.
Portsmouth City Council leader Donna Jones attended, and raised the Commonwealth Flag with the Lord Mayor.
She said: ‘The Commonwealth is more important now than ever, particularly when we are facing the trade negotiations post Britain leaving the European Union.
‘The shared values of the Commonwealth are democracy, negotiation, partnership, friendship, and respecting each other’s cultures.
‘Having members of the armed forces who are citizens from around the Commonwealth, serving in the British navy is a fantastic example of how this is still important in 2017.’
In Havant, the Union flag was raised outside Havant Borough Council’s Public Service Plaza in support of Commonwealth Day.
The Commonwealth Flag was raised at the Ferry Gardens in Gosport, and the Mayor of Gosport Cllr Lynn Hook attended a ceremony at County Hall in Winchester.
No flags were raised in Fareham.