The name Lilibet has been chosen in honour of the baby's great-grandmother, Queen Elizabeth II, a family nickname the monarch has had since childhood; while Diana is a touching nod to Prince Harry's late mother, Princess Diana.
Click though the gallery above to see all of the Queen and Prince Philip's grandchildren and great-grandchildren.
While she may be the first royal tot to receive the unique nickname as a moniker, Lilibet is not the first, and likely won't be the last, to be named after the Queen.
In fact, British royals have a long tradition of keeping names in the family. Here, we explore which members of the royal family have been named after Queen Elizabeth II and Prince Philip.
Royals named after Queen Elizabeth II
Queen Elizabeth II was born Princess Elizabeth Alexandra Mary Windsor, to the Duke of York, Albert Frederick Arthur George, and her mother, Elizabeth Angela Marguerite Bowes-Lyon, who went on to become King George VI and Queen Elizabeth.
The Queen herself was named after her mother, and it's a name that has since been passed down through royal generations.
Lilibet's name has drawn the most comparisons with Prince William's daughter, Princess Charlotte Elizabeth Diana, 6. Much like Lilibet, or Lili, the daughter of the Duke and Duchess of Cambridge was named after her paternal great-grandmother and grandmother.
The Queen named her only daughter Princess Anne Elizabeth Alice Louise. Princess Anne, 70, passed the name down to her daughter, born Zara Anne Elizabeth Phillips. Phillips, however, is not to be confused with Prince Philip's name; it is the surname of the Princess Royal's first husband, Mark Phillips.
Zara, now Zara Tindall, 40, has two daughters of her own and her second-born was named Lena Elizabeth Tindall, 2, in honour of her great-grandmother. Her brother, Peter Phillips, 43, and ex-wife Autumn Phillips named their second daughter Isla Elizabeth, 9.
Like his sister, Princess Anne, Prince Andrew, 61, named his eldest daughter after his mother, calling her Princess Beatrice Elizabeth Mary. Princess Beatrice, 32, is currently pregnant with her first child with husband Edoardo Mapelli Mozzi.
In keeping with tradition, Prince Edward, 57, the youngest son of the Queen and Prince Philip, is father to Lady Louise Alice Elizabeth Mary, 17.
Royals named after Prince Philip
It is not just female royals who have been given the honorific treatment, however, with many male royals honouring Prince Philip with the names of their children.
Prince Charles Philip Arthur George, the Queen and Prince Philip's eldest child, was named after his father, and also his maternal grandfather, King George VI.
In turn, Prince Charles, 72, passed the name down to his eldest son, Prince William Arthur Philip, 38. However, the Duke and Duchess of Cambridge did not continue the tradition with their sons, naming them Prince George Alexander Louis, 7, and Prince Louis Arthur Charles, 3.
Prince Edward and Sophie, Countess of Wessex named their son James Alexander Philip Theo, now aged 13 and known as James, Viscount Severn.
The name Philip has been passed down to the generation of great-grandchildren in 2021, with the birth of Princess Eugenie, 31, and Jack Brooksbank's baby boy, August Philip Hawke Brooksbank, on February 9, and Zara and Mike Tindall's son, Lucas Philip Tindall, born on March 21.
The full names of Queen Elizabeth II and Prince Philip's children:
- Prince Charles Philip Arthur George, born November 14, 1948
- Princess Anne Elizabeth Alice Louise, born August 15, 1950
- Prince Andrew Albert Christian Edward, born February 19, 1960
- Prince Edward Antony Richard Louis, born March 10, 1964
The full names of Queen Elizabeth II and Prince Philip's grandchildren:
- Peter Mark Andrew Phillips, born November 15, 1977
- Prince William Arthur Philip Louis, born June 21, 1982
- Zara Anne Elizabeth Phillips, born May 15, 1981
- Prince Harry, Henry Charles Albert David, born September 15, 1984
- Princess Beatrice Elizabeth Mary, born August 8, 1988
- Princess Eugenie Victoria Helena, born March 23, 1990
- Lady Louise Alice Elizabeth Mary, born November 8, 2003
- James Alexander Philip Theo, Viscount Severn, born December 17, 2007
The full names of Queen Elizabeth II and Prince Philip's great-grandchildren:
- Savannah Anne Kathleen Phillips, December 29, 2010
- Isla Elizabeth Phillips, born March 29, 2012
- Prince George Alexander Louis, born July 22, 2013
- Mia Grace Tindall, born January 17, 2014
- Princess Charlotte Elizabeth Diana, born May 2, 2015
- Prince Louis Arthur Charles, born April 23, 2018
- Lena Elizabeth Tindall, born June 18, 2018
- Archie Harrison Mountbatten-Windsor, born May 6, 2019
- August Philip Hawke Brooksbank, born February 9, 2021
- Lucas Philip Tindall, born March 21, 2021
- Lilibet 'Lili' Diana Mountbatten-Windsor, born June 4, 2021