Her new positions include Patron of Action on Addiction, Royal Patron of East Anglia's Children's Hospices, Royal Patron of The Art Room and Patron of the National Portrait Gallery based in London.
The charities were picked by Kate herself after spending months researching the charitable the sector.
St James's Palace said on Thursday that the Duchess of Cambridge, who turns 30 on Monday, has accepted honorary positions with charities that deal with a range of issues, including tackling drug addiction and helping young people.
A former Brownie guide, Kate will also serve as a volunteer for the Scout Association.
One of the charities, Action for Addiction, spoke of their delight that the princess chose to be a patron of their charity. Her Royal Highness recently paid a private visit to one of Action on Addiction’s treatment centres and spoke at length to a number of clients about their addiction and personal journeys to recovery.
Chief executive Nick Barton said: “It is a great honour for the charity that Her Royal Highness has chosen to become our patron. We are very grateful to the Duchess whose support will enable us to keep the issue of addiction in the spotlight.
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“Addiction is a consuming condition that results in a great deal of harm to individuals, families, communities and society as a whole.
“Yet, it is not always well understood or responded to effectively. We are thrilled that the Duchess will be supporting us in our mission to free people from addiction and its effects.”
Supporting charities is considered important for members of the Royal Family. Prince William is the Patron of Centrepoint – the UK’s leading homelessness charity – the Patron of Tusk Trusk and the Patron of Mountain Rescue of England and Wales – among many others.
The Duchess will also be following in the footsteps of William’s mother Princess Diana was also the Patron of Centrepoint, National AIDs trust and a campaigner for the British Red Cross Anti-Personnel Land Mines Campaign.
Kate is already the Patron of the Foundation of Prince William and Prince Harry.