Abstract: An improved utility box for a vehicle having a cargo area that releasably attaches to the inner surfaces of the side walls of said cargo area without penetrating any surface of the vehicle. The utility box features a locking mechanism that protrudes from the side surfaces of the utility box to releasably engage with the inner surfaces of the sides of the cargo area. The locking mechanism can be a ratchet mechanism or a spring-loaded or cam-actuated telescoping bar. Preferred embodiments include a grommet or other sealing structure featured in the openings through which the locking mechanism protrudes. Still other embodiments include a foot pad made of a resilient, cushioning material at either end of the locking mechanism to provide cushioning and to protect the surfaces of the cargo area.