Kensington Palace said Harry - known in the army as Capt. Wales - will be organizing significant commemorative events involving the army in his new role.
Harry, 29, spent more than three years training to be and serving as an Apache helicopter pilot, completing a tour in Afghanistan last year as a co-pilot gunner.
In July, he qualified to command an Apache - the culmination of his training.
Harry now will be a staff officer at HQ London District, which plans ceremonial events such as Trooping the Color and state visits.
His new role could involve helping bring the Warrior Games to the U.K. - something Harry said he was keen to see happen after attending the event last year in Colorado.
The Warrior Games are a Paralympic-style event for wounded service members.
Kensington Palace said feasibility work is being carried out about the possibility of Britain hosting the inaugural International Warrior Games.