A telescopically extendable truck bed shell including a shield assembly, a transmission assembly. The shield assembly includes shields telescopically connected together. The shields are configured to be mounted on top of a truck bed and attached at side rails. The transmission assembly includes a motor which drives motion to a threaded rod that is internally connected to the shields by means of bearing units and transmission gears. The motor is electrically powered and remotely controlled to permit a user to retract or extend the shields wirelessly. When contracted, the shields permit a user to easily retrieve items inside the truck bed.