It's to pay respects to people who've lost their lives in wars and those who are still fighting.
A national event will be held in Stirling which will feature a Red Arrows fly past.
Armed Forces Day was established in 2009 to recognise the contribution of Britain's servicemen and women.
Executive officer at Armed Forces Christian Union, Val Hall, told Premier's News Hour the organisation has a prayer for the day online.
Bishop of Birmingham, Rt Revd David Urquhart, tells Premier it's an important day.