The change in interfacial properties of the blends of immiscible linear A and B homopolymers by the addition of A-B ring gradient copolymers is investigated through a self-consistent field theory. The length of the composition gradient along copolymer chain contours is signified by a gradient number lambda spanning 0 to 1. It is shown that the ternary blends with the ring copolymers are affected by screening unfavorable A/B contacts, the doubling-back of copolymer conformations, and the solubility of copolymers in homopolymer-rich phases. Upon the interplay of these effects, interfacial tension and thickness along with the surface adsorption of the copolymer chains in the blends yield mostly a monotonic dependence on lambda with some peculiar lambda regions, where the former two properties reveal a reverse trend. Discrepancies in such interfacial properties between the blends with the ring copolymers and with the corresponding linear copolymers are attributed again to the action of those determining effects.