In 2000, Et and Esi introduced new type of generalized difference sequences by using the structure of C¸ olak’s work from 1989 where he defined new types of sequence spaces while C¸ olak was also inspired by Kızmaz’s idea about the difference operator he studied in 1981. In this study, we consider Et and Esi’s work and study Ko¨the-Toeplitz duals of their generalized difference sequence spaces. We take their study in terms of fixed point theory and find large classes of closed, bounded and convex subsets in those duals with fixed point property for nonexpansive mappings.