A joining device for parts of furniture and furnishing accessories includes a casing or container body suitable for being inserted in a seat formed in one of the components of the item of furniture to be joined and provided with an expansion bushing externally projecting with respect to a first end or front end of said casing or container body and suitable for engaging with a further seat of a further component of the item of furniture to be joined to the component wherein the casing or container body is inserted. Said joining device includes a cam mechanism for a linear motion of actuation means co-operating in an expansion and retraction deformation movement of the expansion bushing and simultaneous expansion of at least one portion of said casing or container body, with said cam mechanism and actuation means housed in the casing or container body and actuated by a tool.