She is known to many today as the Princess of Wales, but depending on the time and location, that was not always the case.
Since Kate officially joined the royal family in 2011 when she married Prince William, she inherited an official royal title, but it wasn't the same title many know her as now.
And when the royal family, 42, is in Scotland or Northern Irelandher official titles may again vary.
Kate also has several military titles that she has acquired over the years, including Colonel of the Irish Guards.
Here, FEMAIL reveals Kate's titles, what they mean and the right time to use them.
Before Kate became Princess of Wales, she was known as the Duchess of Cambridge (photo in 2022)
Princess of Wales
Kate now holds the title of Princess of Wales – the first member of the Royal Family to hold the title since then Princess Diana died in 1997.
When Kate acquired the title, a source close to her said she was 'appreciates the history associated with this role but will understandably want to look to the future as she creates her own path'.
'The couple is focused on deepening the trust and respect of the people of Wales over time.
“The Prince and Princess of Wales will approach their roles in the modest and humble way they have previously approached their work,” the source said.
In his first televised address to the nation after the queen's death, King Charles III confirmed that his son, Prince William, would inherit his title of Prince of Wales and his wife Kate would become a princess.
Kate became the Princess of Wales after the death of Queen Elizabeth II (pictured at Buckingham Palace after the coronation of King Charles III and Queen Camilla at Westminster Abbey)
The Princess of Wales is the Colonel of the Irish Guards. In the role, she presented traditional sprigs of shamrock to officers and guards of the Irish Guards during the 2023 St. Patrick's Day Parade at Mons Barracks (pictured)
The king said at the time: 'Today I am proud to create [William] Prince of Wales, Tywysog Cymru, the country whose title I have been so immensely privileged to bear for so much of my life and duty.
“With Catherine by his side, I know our new Prince and Princess of Wales will continue to inspire and lead our national conversations, helping to bring the marginalized to the center where vital help can be provided.”
Since the 14th century, the title Princess of Wales has been used by the wives of the Princes of Wales. However, it is a courtesy title.
Technically, Charles' wife, Camilla Parker-Bowles, was the Princess of Wales until Queen Elizabeth's death, but she used the feminine equivalent of Charles's Duke of Cornwall title, the Duchess of Cornwall.
The Duchess of Cornwall did not use the title Princess of Wales out of respect for Charles' ex-wife Princess Diana, who died in Paris in August 1997.
Duchess of Cornwall
Following the death of Queen Elizabeth II and the ascension of Charles in 2022, Kate inherited an additional title from Queen Consort Camilla.
Kate acquired the title Duchess of Cornwall – a courtesy in direct lineage to the rank of the King and Queen.
The title is held by the heir apparent to the British throne, and in this case Prince William.
Before Kate used the title, Queen Camilla was named Duchess of Cornwall after her marriage to Charles in 2005.
Charles' eldest son, William, 41, also inherited the title of Duke of Cornwall after the queen's death.
The royal family was known as the Duchess of Cornwall and Cambridge on September 8, marking the transition period between Queen Elizabeth's reign and her son's confirmation as the new king.
Once Charles was confirmed as monarch, Kate became the Princess of Wales.
Duchess of Cambridge
On her wedding day to Prince William in 2011, Kate acquired the title of Duchess of Cambridge
Kate is pictured above as Duchess of Cambridge at the Earthshot Prize Awards ceremony in London, 2021
Kate officially became a member of the Royal family on April 29, 2011, after she got married Prince William.
On her wedding day, the 42-year-old dropped her first and last names, ranging from Catherine Elizabeth Middleton to plain Catherine, Duchess of Cambridge.
Duchess of Rothesay and Countess of Chester
When Kate travels to Scotland these days, she goes by the titles Duchess of Rothesay and Countess of Chester.
In the same way, William became the Earl of Chester, linked to the Prince of Wales.
Before becoming Princess of Wales, Kate held the title Countess of Strathearn – a title she still holds today.
Countess of Carrick and Baroness of Renfrew
Kate holds regional titles when she travels to Northern Ireland, namely Countess of Carrick and Baroness of Renfrew.
The title comes from William's inherited title, Earl of Carrick.
Kate's regional titles in Northern Ireland are Countess of Carrick and Baroness of Renfrew.
Kate's military titles
Colonel of the Irish Guards
Kate took over from William as Colonel of the Irish Guards in 2023, making her the 11th Colonel. In March 2023, she received her first salute at a St. Patrick's Day parade.
Commodore-in-Chief of the Fleet Air Arm
The Princess became Commander-in-Chief of the Fleet Air Arm from August 2023.
The title was previously held by Prince Andrew before it was stripped from him and returned to the Queen when he faced a civil sex abuse lawsuit that he later paid millions to settle.
Colonel-in-Chief of the 1st Queen's Dragoon Guards
Kate was appointed Colonel-in-Chief of the 1st Queen's Dragon Guards in 2023.
The mother of three was given the title by King Charles. She made her debut in the role last November during a visit to Robertson Barracks.
Royal Honorary Air Commodore of RAF Coningsby
At the same time that Kate received the tile of Colonel-in-Chief of the 1st Queen's Dragon Guards, she also became Royal Honorary Air Commodore of RAF Coningsby.
Kate took over from her husband Prince William, who had held the title since 2008.
Royal Honorary Air Commodore of the Air Cadets
In 2020, at the age of 33, Kate became the Royal Honorary Air Commodore of the Air Cadets.
The role, Kate's first military title, includes the Air Training Corps and the Combined Cadet Force.