The King’s nephew Peter Phillips is engaged to NHS nurse Harriet Sperling.
Princess Anne’s eldest son, 47, went public with the paediatric nurse, 45, last May when they were spotted hand-in-hand at the Badminton Horse Trials in Gloucestershire.
Phillips has since been spotted with Sperling - who has her own separate connection to the royal family - at multiple events, including Wimbledon, the Cheltenham Races and Royal Ascot.
The couple have informed the King and Queen of their engagement and are yet to set a date for the wedding.
"Mr Peter Phillips, the son of HRH The Princess Royal and Captain Mark Phillips and Ms Harriet Sperling, daughter of the late Mr Rupert Sanders and Mrs Mary Sanders of Gloucestershire, have today confirmed their official engagement,” they said in a statement.
"Both families were informed jointly of the announcement and were delighted with the wonderful news of their engagement.”
The statement went on: "Their Majesties The King and Queen, The Prince and Princess of Wales have been informed of the announcement.
"No date has been officially set for the wedding."
Sperling has a link to the royal family in her own right as she is related to the Duke of Gloucester through her late father.
She is thought to be a devout Christian who has written about the “struggles” of raising her daughter as a single mother in the past.
“The unique relationship between a single mother and her child is forged in the fires of struggles and victories,” she wrote, per MailOnline.
“It’s a bond characterised by a love and survival against the odds.
“But of course beauty comes from relationships, relationship with our maker and relationship with each other.
“It is often tough parenting alone but although there is a stigma to endure, God is able to step in and turn it for good.”
Phillips - who is 18th in line to the throne - and Sperling began dating just weeks after he split from Lindsay Wallace after three years together.
He has two daughters - Savannah, 14, and Isla, 13 - from his previous 12-year marriage to Autumn Kelly.
