Prince William is to leave the military after more than seven years of service.
The Duke of Cambridge completed his final shift as an RAF search and rescue pilot on Tuesday.
Kensington Palace said he will now focus on royal duties and charity work together with the Duchess of Cambridge.
The palace said the duke is considering a number of options for public service and will make a further announcement in due course.
The BBC reports Tuesday's final RAF shift brought to an end a three-year posting on Anglesey for the prince.
The Duke and Duchess of Cambridge are expected to move from their home there to Kensington Palace in the next few weeks.
In a speech at Anglesey Show in August, the duke thanked the island's people for being so welcoming to him and his wife.
"I know that I speak for Catherine when I say that I have never in my life known somewhere as beautiful and as welcoming as Anglesey," said the duke.
"I know that both of us will miss it terribly when my search and rescue tour of duty comes to an end next month and we have to move elsewhere.
"From the bottom of my heart, thank you for making my wife and me so welcome when we arrived here, as you do thousands of visitors each year."