We investigate the imprint of dark energy on the kinetic Sunyaev–Zel'dovich (kSZ) angular power spectrum on scales of ℓ=1000 to 10000, and find that the kSZ signal is sensitive to the dark energy parameter. For example, varying the constant w by 20% around w=−1 results in a ≳10% change on the kSZ spectrum; changing the dark energy dynamics parametrized by wa by ±0.5, a 30% change on the kSZ spectrum is expected. We discuss the observational aspects and develop a fitting formula for the kSZ power spectrum. Finally, we discuss how the precise modeling of the post-reionization signal would help the constraints on patchy reionization signal, which is crucial for measuring the duration of reionization.