The ceremony starts at 10am and will be led by the district council chairman Jenny Bloom.
Ira Bhattacharya from the Aylesbury Indian Cultural Society will raise the flag during the ceremony.
Guests will include the Countess of Buckinghamshire and representatives from local community groups.
Cllr Bloom, who will deliver a reading of the Commonwealth Affirmation at the ceremony said: “Commonwealth Day gives us the perfect opportunity to celebrate the diversity of our local community and join together to affirm our commitment to uphold the values set out in the Commonwealth Charter.”
More than 1000 Commonwealth flags will be raised in locations throughout the United Kingdom, Channel Islands, Isle of Man, UK Overseas Territories, and Commonwealth countries on that date.