A foldable sofa armrest and a sofa are provided. The foldable sofa armrest includes an armrest frame and an armrest skin, where the armrest skin covers an outer surface of the armrest frame; the armrest frame includes a first frame, a second frame, and a folding part; the folding part includes a first folding member, a second folding member, and a connecting component; the first folding member is provided on the first frame; the second folding member is provided on the second frame; the armrest frame has a first state and a second state; in the first state, the connecting component securely connects the first folding member to the second folding member; and in the second state, the first folding member and the second folding member are rotatable relative to each other. The sofa armrest is allowed to be in an unfolded or folded state.