A portable backrest gives upper body support to a person sitting sideways on a sofa or like furniture, the portable backrest placed and retained on the sofa through a cushion of the sofa on which the person eventually sits. A lower, support or base portion of the portable backrest forming a bracket that is received under and around a part of the cushion that is adjacent an armrest of the sofa while an upper portion of the portable backrest extends upwardly and outwardly from the lower portion and armrest to support the upper body, neck and head of a sitting person. In one form, a back portion of the backrest is pivotally connected to a lower portion of the backrest while in another form, the back portion is integral with the lower portion. The upper portion may have back, neck and head cushioning.