A slide rail assembly includes a first rail, a second rail movably connected to the first rail, a bracket base connected to the first rail, and a supporting base movably mounted to the bracket base. The supporting base includes a wall portion and at least one supporting portion transversely connected to the wall portion. The wall portion and the at least one supporting portion jointly define a supporting channel corresponding to a longitudinal channel defined by the first rail. The at least one supporting portion of the supporting base supports the second rail as the second rail is longitudinally displaced relative to the first rail and extends through the longitudinal channel of the first rail and the supporting channel of the supporting base.