A half‐mode substrate integrated waveguide (HMSIW) leaky‐wave antenna with a folded ground is proposed in this article to realize continuous beam scanning from backward to forward direction. This leaky‐wave antenna is designed within its scanning region from −27° to 23° as the operating frequency increases from 10 to 14 GHz. In addition, this antenna has a high radiation gain even at broadside. As a folded ground is used to reduce the energy leakage from the open boundary in HMSIW, the transverse size of the proposed antenna could be further miniaturized against other reported HMSIW leaky‐wave antennas. Our results show that the radiation gain of the antenna can stably vary from 10 to 11.5 dB by using the open‐stopband suppressed technique at broadside. Measured results are found in good agreement with simulated ones over a wide frequency range.