We define the worldline harmonic superspace and its analytic subspace as a deformation of the flat harmonic superspace. The harmonic superfield description of the two mutually mirror off-shell supermultiplets is developed and the corresponding invariant actions are presented, as well as the relevant classical and quantum supercharges. Whereas the σ-model actions exist for both types of the multiplet, the invariant Wess–Zumino term can be defined only for one of them, thus demonstrating non-equivalence of these multiplets in the case as opposed to the flat supersymmetry. A superconformal subclass of general actions invariant under the trigonometric-type realizations of the supergroup is singled out. The superconformal Wess–Zumino actions are shown to possess an infinite-dimensional supersymmetry forming the centerless super Virasoro algebra. We solve a few simple instructive examples of the supersymmetric quantum mechanics of the multiplets and reveal the representation contents of the corresponding sets of the quantum states.