Abstract: With increase in the number of operations involving relief wells, radial wells, U-shaped wells, and other complex well structures, challenges such as collision prevention, obstacle bypassing, and adjacent-well connectivity achievement during drilling have become inevitable. These challenges necessitate a technology that can accurately detect adjacent wells in real time during drilling operations. As current borehole acoustic reflection imaging technology heavily relies on cable-based logging, it cannot perform real-time detection of adjacent wells during drilling, thereby limiting the drilling efficiency. This study proposes a new adjacent-well-acoustic-detection-while-drilling method that integrates wireline borehole acoustic reflection imaging with drilling technology, along with an adjacent-well imaging method based on compressed sensing (CS). Together, these methods enable high-resolution, real-time detection of the adjacent target wells during drilling, ensuring safe and efficient underground drilling operations. The finite-difference method was used to simulate three-dimensional numerical models under drilling conditions for two scenarios—with and without target wells adjacent to the drilling well. Experimental validation was conducted in a water tank using an adjacent-well-acoustic-detection-while-drilling tool. The simulated target well was imaged using the CS method, and the imaging results were compared with those obtained from numerical and physical simulations, thereby validating the feasibility of the proposed acoustic detection and imaging methods. The results demonstrate that as the radial distance from the target well increases, the PP echo exhibits delayed arrival times and approaches a plane wave while exhibiting amplitude attenuation. Conversely, a linear increase in the target well diameter advances the PP echo arrival time and enhances its amplitude proportionally. When the target and drilling wells are approximately parallel with a small intersection angle, PP echoes yield better detection results than SS echoes; when the wells are coplanar with a large intersection angle, SS echoes provide better detection results. The receiver element aligned with the target well’s azimuth detects all echo modes with the earliest arrival times and highest amplitudes. The adjacent-well imaging method based on CS offers very high spatial resolution, with target wells appearing as local amplitude maxima. This feature enables the precise determination of their azimuth and inclination relative to the drilling wells. The findings offer a solid physical and methodological foundation for real-time detection of adjacent wells during drilling operations and demonstrate enormous theoretical and engineering application potential.