Events get underway with a military parade at 11am from Sir Nigel Gresley Square.
The parade will make its way through the city and pass the Mansion House, ending at Market Square.
From 11.30am onwards, there will be interactive/information stalls, exhibits, live music and entertainment in the Market Square, a vehicle display from Royal Logistic Corps 150 Regiment 219 Transport Squadron, free face painting and opportunity to learn to hand jive with DN4Dance.
Doncaster mayor Ros Jones said: “Armed Forces Day is an opportunity to come together to express our appreciation and gratitude to our brave servicemen and women.
“Doncaster is very proud of its armed forces community and everyone is welcome to attend the event on Saturday in recognition of our Armed Forces’ selfless contribution and all the sacrifices they have made and continue to make.”