<p>This paper offers a novel exploration of the stability of fractional integro–differential equations with finite delay and almost sectorial operators. We present new theorems that address both Hyers–Ulam–Rassias and Hyers–Ulam stability for these equations on bounded and unbounded intervals. The proofs are based on the fixed point method, which provides a solid foundation for our analysis. To demonstrate the practical significance of our theoretical results, we include several examples that confirm their effectiveness. The findings on Hyers–Ulam–Rassias and Hyers–Ulam stability contribute meaningfully to the understanding of Ulam stability for fractional integro–differential equations and extend the existing literature in this field.</p>