<p>Hydraulic power take-off (PTO) in point-absorber wave energy converter (WEC) models is commonly represented by numerically smoothed Coulomb damping, yet this simplification neglects the series-coupled stiffness that governs force evolution during stick–slip transitions. To address this limitation, a bilinear hysteretic (Jenkins-type) damping model is adopted as a physically consistent equivalent representation of hydraulic PTO nonlinearity. The heave dynamics of a point-absorber WEC under regular wave excitation are investigated within a nonlinear frequency-domain framework and verified against time-domain simulations. A harmonic balance formulation is employed to derive a complex dynamic stiffness representation of the Jenkins-type force in the frequency domain, while high-fidelity steady-state solutions are further obtained via the alternating frequency–time harmonic balance (AFT–HB) method. Parametric studies show that the series-coupled stiffness strongly affects the smoothness of stick–slip transitions and the amplitude–frequency response, and that conventional Coulomb models may overestimate the energy capture. This Jenkins-type equivalent PTO model, characterized by the series-coupled stiffness and the friction threshold, extends the conventional Coulomb-type approximation and, together with the harmonic-balance-based frequency-domain solution method, provides an efficient approach for assessing the energy-capture performance of hydraulic PTO point-absorber WECs.</p>