After leaving the plane through a window using a rope, the co-pilot then surrendered to police asking for asylum in Switzerland.
Flight ET702 was “forced to proceed” to Geneva international airport after a mayday plea was issued.
Police now have the situation “under control” and there are no injuries to passengers or crew.
The aircraft was on its way from Addis Ababa and was scheduled to arrive in Rome at 4.40am. Instead it landed in Switzerland at 6am local time.
The pilot is reported to have issued a mayday as the plane flew over Sudan.
Sky News’s Harriet Hadfield said the airport had not yet opened when the plane landed – and passengers had to wait until it did before disembarking.
She said: “It must have been a very terrifying experience for the passengers on board.