Defending champion and US Open finalist Jessica Pegula has also pulled out from the WTA 500 event in Seoul with a rib injury.
Poland's Swiatek, who won the French Open in June and took bronze in the Paris Olympics before losing to Pegula in the US Open's quarter-finals, had also withdrawn from last month's Canadian Open citing fatigue.
Former Wimbledon champion and world number four Elena Rybakina will also miss the Korea Open with a back injury, while US Open semi-finalist Emma Navarro has pulled out due to a change of schedule.
The Korea Open will take place between September 16th-22nd.