The mouth tray for teeth whitening includes a horseshoe-shaped main body made up preferably of a flexible material and anatomically contoured to fit exactly to the upper and lower sets of adult human teeth. The surface of the mouth tray has a plurality of elevated crisscross patterns to keep the whitening agent in place throughout the procedure. Both the ends of the mouth tray have elevated horizontal ridges with reduced elevation towards the interior portion of the mouth tray prevents the seeping and falling of the whitening agent during the process. A predetermined quantity of whitening gel may be prefilled on the mouth tray. The user just needs to attach the prefilled mouth tray to a suitable lighting device and place the mouth tray inside the mouth.