Police were told that a man with a gun was in the Clayton Hotel on Sunday evening, threatening staff and guests.
The police said officers were on the scene within minutes and when they arrived, a man had been taken hostage.
Specially-trained officers arrived shortly afterwards and the hostage was released. A 31-year-old man was later arrested.
The incident began at about 18:45 BST and police cordons remained in place for several hours.
"The suspect attempted to make off from the scene, but was detained by police. It was confirmed that the item was not a firearm," said a police spokesman.
"I want to thank the staff and patrons present for their cooperation during what was a terrifying ordeal. Thankfully, no-one is believed to have been physically harmed."
During the incident, Ormeau Avenue in Belfast city centre was cordoned off, and armed police and sniffer dogs could be seen entering the hotel.
BBC News NI was told that some guests who were in their rooms were advised to stay there.
Police officers remain at the scene.