Abstract: The extendable truck bed comprises and extension bed floor and extensible side panels that allow the cargo bed of a pickup truck to be expanded so as to provide an increased cargo capacity. The extendable truck bed moves from a ‘nominal bed length’ position to an ‘extended bed length’ position under control of one or more operator controls that may be located in the cab of the truck. In the ‘nominal bed length’ position the extension bed floor is located beneath the truck bed floor and the extensible panels are located in a left side panel pocket and a right side panel pocket in the side walls of the truck bed. A left side motor and right side motor drive a left side flexible linkage and a right side flexible linkage to move the extension bed floor and extensible side panels to the ‘extended bed length’ position.