To address the trade-off between transient response and steady-state precision in single-phase full-bridge inverters, this paper proposes an adaptive Proportional-Integral-Derivative (PID) fusion control strategy based on manifold-oriented dynamic weight allocation. This paper proposes an adaptive PID fusion control strategy based on manifold-oriented dynamic weight allocation. The strategy integrates a double-closed-loop PID controller and a sliding mode controller (SMC) using a nonlinear mapping guided by the sliding mode manifold. By dynamically balancing these control laws, the strategy effectively reduces overshoot to 0.12%, a common issue in linear control, while also suppressing steady-state chattering and harmonic distortion typical of standalone SMC. The system’s stability is rigorously verified using Lyapunov theory. Simulation results demonstrate that the fusion strategy effectively suppresses startup overshoot, reducing it to 0.12%, compared to 1.7 V in conventional PID control. Under steady-state conditions, the proposed method maintains an error envelope of 0.4V and reduces Total Harmonic Distortion (THD) to 1.32%, compared to 4.44% for PID and 3.80% for SMC. Furthermore, the strategy exhibits superior disturbance rejection during load mutations, ensuring high waveform quality and rapid dynamic recovery. This framework effectively couples the high-gain robustness of nonlinear control with the high-precision smoothing of linear control, providing an optimized, theoretically rigorous solution for high-performance power quality control in inverter applications.