Ocean wave energy has played a key role of the renewable energy. This study presents a novel single-buoy wave energy converter (WEC) with directly driven power take-off (PTO) system to overcome some difficulties that the PTO system in the conventional single-body direct-drive WEC (DD-WEC) is fully submerged under water and far away from the water surface. A rectangular buoy, a direct-drive PTO system with Halbach permanent magnet linear generator (HPMLG), and slide rails form the chief institutions of the WEC. The translator of the HPMLG is installed on the lateral surface of buoy, and the stator is mounted on the seacoast or the boats and ships. While wave drives the floating buoy to move, a relative movement between the translator and the stator of the HPMLG is caused. Then, the relative movement generates electricity. To explore theoretically its feasibility, the dynamics of the wave and the floating buoy is analyzed in detail. Thus, the structural parameters are analyzed and determined, and load performance is described. Furthermore, the finite element method (FEM) is used to conduct the performance evaluation of the HPMLG and traditional permanent magnet linear generator (TPMLG). The generated power of the HPMLG is 19% higher than the TPMLG under the same conditions. Lastly, Experiments of a fabricated prototype are conducted in the wave tank. Experimental results show that the prototype in this paper decreases these existing problems and is suitable for wave energy generation.