The princess was previously seen arriving in a royal helicopter.
She appeared at a garden party at Hillsborough Castle and Gardens this afternoon, greeting guests with Northern Ireland’s Foreign Secretary Brandon Lewis.
It is the first annual garden party to be held at the castle since the start of the Covid pandemic.
The party was held in honor of community workers.
Anne also visited Ballymena in Co Antrim and an equine rehabilitation center as part of her one day trip to Northern Ireland.
The visit started with a trip to Ballymena Showgrounds.
There is a flagship celebration to mark 100 years of cadets from across Northern Ireland at St John’s Ambulance.
Anne met leaders as well as cadets and badgers and learned about the organization’s offerings of youth programs and activities.
The Royal Family tweeted: “Celebrating 100 years of St John’s Ambulance Cadets!
“Since 1922, the Cadets have enabled young people to learn essential first aid skills and build confidence.”
The princess also met several young people who were completing the Duke of Edinburgh Award program.
She later attended the Irish Equine Rehabilitation Center in Lower Ballinderry in Co Antrim.
Here she surveyed the stable and saw a demonstration of a water treadmill and saltwater hydrotherapy used in equine rehabilitation.
The party at Hillsborough Castle represents her last of the day, where she appeared as a bridesmaid.
Mr Lewis presented Anne with a Platinum Jubilee basket, a gift produced as part of a Northern Ireland Office initiative.
Before leaving, Anne planted an oak tree in the castle’s walled garden.
The Princess Royal recently announced that she has no intention of slowing down as she approaches her 72nd birthday.
She has agreed to become the patroness of an association previously supported by her father, the late Duke of Edinburgh.
The organisation, BAPRAS (British Association of Plastic Reconstructive and Aesthetic Surgeons) aims to raise awareness of the breadth of plastic surgery and promote innovation in the field and understanding of the profession.
Sharing the news, the association said in a statement: “BAPRAS is delighted to announce that Her Royal Highness, The Princess Royal has agreed to become its Royal Patron.
“HRH Princess Anne is considered one of the hardest working members of the Royal Family and with her support for the military services, we felt she would have a connection to the work and origins of our association.”
The statement added a moving tribute to Prince Philip, who died in April last year.
It read: “For the past 57 years, until his sad passing in 2021, we have benefited from the patronage of His Royal Highness The Duke of Edinburgh, who has been an inspirational figure and vocal supporter of the Association.”
Over the course of his life, the late Duke became involved in more than 990 charities and associations.
Some of these patronages were passed on to other members of the Firm, such as the British Trust for Ornithology, now led by the Duke of Cambridge.
However, many others lost their ties to the royal family after the death of the queen’s husband.