All 299 passengers on board the Eurowings flights were evacuated but no explosives were found on board, authorities said.
The plane was heading to Cologne from Salalah when the captain requested an emergency landing in Kuwait City, the state-run KUNA news agency of Kuwait said.
Mansour al-Hashemi, a spokesman for Kuwait's civil aviation authority, said: "Initial investigations confirmed the plane was explosives-free."
The plane was diverted to Kuwait "for security reasons and in consultation with the relevant authorities," Eurowings said in a statement.
Eurowings is a subsidiary of Lufthansa, and Tal Muscal, a spokesman for the German airline, confirmed no explosives were found on the plane.
"I do know there is nothing on board," he said.
Eurowings said the plane was being flown by SunExpress on their behalf and the flight was a charter for tour company FTI.
The model of the plane is thought to be an Airbus A330-203 and was scheduled to arrive in Cologne at 9.35am GMT on Sunday.
Agencies contributed to this report.
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