The robbery happened at business premises at the Dobbin Street area of Armagh.
Detective Inspector Trevor Stevenson said: “Shortly after 3pm, it was reported that a man armed with a pair of scissors entered a Bingo Hall and pushed a female staff member to the ground.
“The man made off with a sum of money, but was arrested a short time later.
“He remains in custody assisting us with our enquiries.
“The man was wearing a black jacket, black tracksuit bottoms, black trainers and had a facial injury.
“The female member of staff was not injured during the incident and the pair of scissors were recovered at the scene.
“We would appeal to anyone with any information regarding the incident to contact police in Armagh on 101 quoting 875 12/08/18.
“Alternatively, information can also be provided to the independent charity Crimestoppers on 0800 555 111 which is 100% anonymous and gives people the power to speak up and stop crime.”