The inverter plays a vital role in a wireless power transfer (WPT) system, where its losses are a significant concern. For achieving wide output voltage regulation in WPT systems, phase-shifting (PS) modulation is commonly used, typically without the addition of DC-DC converters. However, this leads to the inverter operating in a hard-switching mode. To address this challenge, a WPT system incorporating an adaptive tuning capacitor (ATC) to extend the zero-voltage switching (ZVS) region has been proposed. In this paper, the phase angle of the ATC is regulated to lag the phase-shifting angle of the inverter by 90°, ensuring a broad ZVS region while minimizing the current in the resonant tank. This approach allows the inverter to operate in soft-switching mode, leading to a significant improvement in system efficiency, particularly under light load conditions. In comparison to conventional WPT systems that rely on switch-controlled capacitors (SCCs) or variable inductors (VIs), the proposed system requires only one feedback loop to regulate. The reduced signal requirements and simplified control strategies offer greater convenience. Finally, the proposed WPT system’s performance is theoretically analyzed and validated through simulations under varying load and magnetic coupling conditions.