The Crown Princess is the youngest daughter of John Dalgleish Donaldson, who was born in Scotland on 5 September 1941. He is a Professor of Applied Mathematics. The Crown Princess's mother was Mrs. Henrietta Clark Donaldson, born 12 May 1942.

The couple were married in Edinburgh, Scotland on 31 August 1963 and emigrated to Australia in November that year. They became Australian citizens in 1975. The Crown Princess's mother worked as the Executive Assistant to the Vice Chancellor of The University of Tasmania. Henrietta Clark Donaldson died 20 November 1997.

On 5 September 2001, Professor John Donaldson married Susan Elizabeth Donaldson (née Horwood), an author from Britain.

The Crown Princess has two sisters and a brother: Jane Alison Stephens, born 26 December 1965, Patricia Anne Bailey, born 16 March 1968, and John Stuart Donaldson, born 9 July 1970.

Wedding
On 14 May 2004, on the occasion of the marriage to His Royal Highness Crown Prince Frederik of Denmark, she became Her Royal Highness Crown Princess Mary Elizabeth of Denmark. The marriage ceremony took place in Copenhagen Cathedral, and the wedding festivities were held at Fredensborg Palace.

Children
HRH Prince Christian Valdemar Henri John, born on 15 October 2005, HRH Princess Isabella Henrietta Ingrid Margrethe, born on 21 April 2007, HRH Prince Vincent Frederik Minik Alexander and HRH Princess Josephine Sophia Ivalo Mathilda, twins born on 8 January 2011.

Residence
The Crown Prince Couple resides both in Frederik VIII’s Palace at Amalienborg and in the Chancellery House at Fredensborg Palace.

The Crown Princess’s schooling began in 1974 and 1975 at Clear Lake City Elementary School in Houston, Texas. Returning to Hobart, The Crown Princess attended Sandy Bay Infants School from 1975 to 1977. From 1978 until 1982, Her Royal Highness attended Waimea Heights Primary School. The Crown Princess attended Taroona High School from 1983 to 1986 and then during the next two years continued her studies at Hobart Matriculation College, where The Crown Princess was also an active sportswoman. Her Royal Highness enrolled at the University of Tasmania in 1989 and graduated in 1994 with a Bachelor's degree in Commerce and Law (B Com. LLB).

Between 1994 and 1996, The Crown Princess qualified for a Certificate in Advertising from The Advertising Federation of Australia (AFA) and later a Certificate in Direct Marketing from the Australian Direct Marketing Association.

Business background
After completion of her university degree, The Crown Princess moved to Melbourne to take a graduate position with the world-wide advertising agency DDB Needham. After completion of the graduate programme, Her Royal Highness held the position of Account Executive for client management. The Crown Princess's career path continued with a position as Account Manager with MOJO Partners, also in Melbourne. In 1998, The Crown Princess travelled around America and also travelled extensively in Europe and the United Kingdom, particularly in her father’s homeland, Scotland, where Her Royal Highness accepted a three-month contract as Account Manager with Rapp Collins Worldwide of Edinburgh.

The Crown Princess returned to Australia in the beginning of 1999 and took a position as Account Director with the international advertising agency Young and Rubicam in Sydney. The Crown Princess later worked for a short time with a smaller Australian company, Love, and Her Royal Highness later became Sales Director and a member of the Management Team with Belle Property.

In the first half of 2002, after deciding to move to Europe, The Crown Princess worked for a short period in Paris, where Her Royal Highness taught English at a Business English School. Later in 2002, The Crown Princess moved to Denmark and was employed by Microsoft Business Solutions as a Project Consultant for business development, communications and marketing.

Military career
The Crown Princess began as a private in the Home Guard in 2008. After training, Her Royal Highness became a sergeant in the Home Guard 2009, lieutenant in the Home Guard 2009, first lieutenant in the Home Guard 2015, captain in the Home Guard in 2019 and honorary major in the Home Guard in 2023

The Crown Princess has taken part in a large number of activities and exercises under the auspices of the Home Guard through the Army-, Navy- and Air Home Guard.

Language
The Crown Princess's mother tongue is English, and Danish is her second language.

The Crown Princess is patron of many national organisations, institutions, and foundations and is an honorary member of various associations and societies.

The Crown Princess has, for many years, focused on being a voice for those who have a hard time in life; on promoting equality and particularly the rights of girls and women as well as supporting sustainable efforts and nature conservation. The fundamental value of creating a society in which everyone feels that they belong is the focal point for many of The Crown Princess’s engagements.

In 2007, The Crown Princess established The Mary Foundation, which has the objective of fighting against social isolation in three priority areas: Bullying and well-being, domestic violence and loneliness. The Crown Princess has been chairman of The Mary Foundation since its establishment. Fighting loneliness and bullying is central in The Crown Princess’s work, and Her Royal Highness emphasizes that everyone has the right to a place in the community. Through her work as, among other things, patron of Danish organizations such as Children, Youth & Grief, The Christmas Seal Foundation and the Danish Mental Health Fund, The Crown Princess especially supports the fight against social isolation for those who are particularly vulnerable or exposed. As patron of the Danish Swimming Federation and The Danish Heart Foundation, among others, Her Royal Highness has also focused on how sports and motion can be a focal point for creating unity and safe communities.

It is a longstanding Danish tradition to help in areas of the world where not all people have the same opportunities that we have in Denmark. This takes place based on Danish values. The Crown Princess supports efforts in which Denmark is a strong voice internationally, and she has special focus on promoting the conditions and rights of girls and women, such as, for example, access to health services and the right to decide about their own bodies and education. The Crown Princess does this, among other ways, as patron of the UN’s Population Fund (UNFPA) and the Maternity Foundation, where the focus is on promoting the sexual reproductive and health rights (SRHR) of girls and women, especially among marginalized groups. As patron of the WHO Regional Office for Europe, The Crown Princess helps to put focus on a number of the most important health topics for the region. In addition, Her Royal Highness is a member of UNFPA’s ICPD25 (International Conference on Population and Development 25) High-Level Commission and the International Center for Research on Women’s Leadership Council.

The Crown Princess’s engagement in sustainability, biodiversity and nature conservation is manifested, among other ways, in The Crown Princess’s work for WWF Denmark, where Her Royal Highness took over as the foundation’s president in 2020. The Crown Princess has also worked for more than a decade to promote the green agenda in the design and fashion industry as patron of Global Fashion Agenda. Sustainable Danish solutions created with a basis in proud Danish craft traditions are in great demand both at home and abroad. Sustainability and innovative, nature-based solutions are therefore often central when The Crown Princess leads business promotional campaigns internationally. Throughout nearly two decades, The Crown Princess has taken part in more than 70 business promotional campaigns, state visits and patronage trips in which The Crown Princess has broadly supported Danish interests in the areas of business, culture and development work.