The aircraft, G-HLYB (c/n 6056), was operating flight LS922 to Manchester but was escorted to land at London/Stansted.
The narrowbody then taxied to a remote part of the airport.
The reason for the escorted diversion is not currently clear, but initial media reports suggest a bomb threat is the likely cause.
In a statement, a Jet2 spokesperson, said: "We can confirm that flight LS922 DLM to MAN diverted to London/Stansted this evening under the direction of UK Air Traffic Control. The aircraft has landed safely and has taxied to a remote stand. We are currently liaising with London Stansted Airport and the relevant authorities."
A spokesperson for Stansted Airport told Key.Aero: "A Jet2.com flight from Dalaman to Manchester diverted to Stansted Airport this evening. The plane landed safely and is parked on a remote stand away from the main passenger terminal. The runway was closed for a short time but has now re-opened.”
Key.Aero has approached Jet2 for comment.