Summary: Making use of operator of fractional calculus, a subclass \(T_\lambda (\alpha, \beta,\mu:k)\) of univalent functions with negative coefficients in the unit disc \(U\) is introduced and basic properties e.g, coefficient estimates and growth theorem are established. Further, we established results involving modified Hadamard product, radius of starlikeness, close-to-convexity and convexity.