An adjustable rack assembly and a cabinet using the same are disclosed. The adjustable rack assembly includes a rail and a sliding component. The rail is extended along a first direction, and includes a rail body, a bent portion and plural positioning grooves. The bent portion protrudes inwardly from an outer edge of the rail body, and the plural positioning grooves are disposed on the bent portion along the first direction. The sliding component includes a sliding body, a limiting portion and a guiding groove. The limiting portion is connected to the sliding body, and the guiding groove and the bent portion are mutually matched. When the sliding component is misaligned with the plural positioning grooves in the first direction, the sliding component is allowed to slide in the first direction. When the sliding component is engaged with the positioning groove, the sliding component is locked on the rail.