The Quantum Chromodynamics (QCD) coupling, αs, is not a physical observable of the theory since it depends on conventions related to the renormalization procedure. We introduce a definition of the QCD coupling, denoted by αˆs, whose running is explicitly renormalization scheme invariant. The scheme dependence of the new coupling αˆs is parameterized by a single parameter C, related to transformations of the QCD scale Λ. It is demonstrated that appropriate choices of C can lead to substantial improvements in the perturbative prediction of physical observables. As phenomenological applications, we study e+e− scattering and decays of the τ lepton into hadrons, both being governed by the QCD Adler function, as well as the scalar correlation function.