oindent In this paper, we introduce some Simpson's type integral inequalities via the Katugampola fractional integrals for functions whose first derivatives at certain powers are $s$-convex (in the second sense). The Katugampola fractional integrals are generalizations of the Riemann--Liouville and Hadamard fractional integrals. Hence, our results generalize some results in the literature related to the Riemann--Liouville fractional integrals. Results related to the Hadamard fractional integrals could also be derived from our results.