The Duke of Cambridge is to carry out his final shift for the East Anglian Air Ambulance (EAAA).
His last duty as a paid pilot for the EAAA will be the night shift from its base at Cambridge Airport.
Writing in the Eastern Daily Press (EDP) Prince William said he had a “profound respect” for those who serve in the emergency services.
He is stepping down to take on more royal duties on behalf of the Queen and the Duke of Edinburgh.
A former RAF search and rescue pilot, the duke is part of a team including doctors and paramedics providing emergency medical cover across Bedfordshire, Cambridgeshire, Norfolk and Suffolk, and to Essex and Hertfordshire at night.
Earlier this year he said: “It has been a huge privilege to fly with the East Anglian Air Ambulance.
“Following on from my time in the military, I have had experiences in this job I will carry with me for the rest of my life, and that will add a valuable perspective to my royal work for decades to come.”
After two years in the role, he told the EDP: “I have met people from across the region who were in the most desperate of circumstances.
“As part of the team, I have been invited into people’s homes to share moments of extreme emotion, from relief that we have given someone a fighting chance, to profound grief.”
Speaking of the “incredibly skilled doctors and paramedics” he has worked with, the prince said: “These experiences have instilled in me a profound respect for the men and women who serve in our emergency services, which I hope to continue to champion even as I leave the profession.
“I am hugely grateful for having had this experience.”
Pilot William Wales, as he is known at work, received a salary for his job which he donated in full back to the EAAA charity.
Get Quotes on Home Insurance
While on duty he works as part of a close-knit team of four, on a nine-and-a-half hour shift, attending the worst medical emergencies of the 2,000-plus calls per day the service receives.
By Peter Hunt, royal correspondent, BBC News
For years – first as an RAF search and rescue pilot and then at the controls of an air ambulance – Prince William has had a job he acquired on merit, and not because of an accident of birth.
He thrived in both environments. According to the future king, it has kept him “grounded”.
He’s loved working in a team. “His other job”, as he once referred to it, doesn’t offer those same advantages.
Little wonder then that today’s last shift – he’ll work through the night – may well be a poignant affair.
Afterwards the prince will no longer have to juggle being an air ambulance pilot with royal commitments.
His critics have grumbled that the House of Windsor needed him to step up to the mark earlier. A tabloid once called him “work-shy Wills”.
Now, aged 35, William is in a position to completely embrace his destiny as a full-time royal and as the future, with his family, of the British monarchy.
The air ambulance charity has attended patients injured by fires, horseback riding accidents, poisoning and road traffic accidents.
“There are some very sad, dark moments. We talk about it a lot, and that’s the best way of dealing with some of these situations,” Prince William revealed in September.
He pilots a H-145 helicopter, which has a maximum speed of 145 knots (170mph) and can be on the scene of an incident in East Anglia within a matter of minutes.
The Prince has been an “integral part” of the service, Patrick Peal, chief executive of EAAA, said.
“He is not only a fantastic pilot, but a much-loved and valued member of the crew. He will be truly missed by everyone at EAAA.
“William… has been a true professional, delivering our doctors and critical care paramedics to patients under testing conditions,” he added.
The Duke and Duchess of Cambridge, whose family home has been in Anmer, Norfolk, have taken up residence in Kensington Palace ahead of their eldest child, Prince George, starting school in September.
A statement issued in January by the palace, said the pair wanted to increase their official duties on behalf of the Queen and their charity work – which would mean more time in London.
“As I hang up my flight suit, I am proud to have served with such an incredible team of people, who save lives across the region every day,” Prince William told the EDP.