An authorised firearms officer (AFO) is a British police officer who is authorised, and has been trained, to carry and use firearms. The designation is significant because in the United Kingdom most police officers do not routinely carry firearms, although they can be equipped with tasers. The only forces where officers are routinely armed are the Police Service of Northern Ireland, the Ministry of Defense Police, the Civil Nuclear Constabulary, Belfast Harbour Police and the Belfast International Airport Constabulary.

In 2019/20 fiscal year, there were 19,372 police operations throughout England and Wales in which the deployment of firearms was authorised and 6,518 firearms officers, 4.9% of the 132,467 active FTE officers. Following the November 2015 Paris attacks it was decided to significantly increase the numbers of armed officers, particularly in London.

AFOs can be up-skilled with additional qualifications, such as Armed Response Vehicle Officer (ARVO), Specialist Firearms Officer (SFO), Counter Terrorist Specialist Firearms Officer (CTSFO) – alongside other specialities, including rifles.