Direct ink writing (DIW) 3D-printed sensors exhibit significant potential in aerospace structural health monitoring due to their design flexibility and high manufacturing precision. This paper reviews recent advances in the design, fabrication, and application of DIW sensors. First, we systematically summarize key breakthroughs in sensor design, including theoretical approaches for multilayer composite structures, optimized layouts for sensor arrays, integrated designs for embedded sensors, and decoupling strategies for multifunctional sensors. Regarding fabrication, we highlight the importance of process parameter optimization for controllable high-precision manufacturing, as well as the development of multi-axis printing systems for conformal deposition on complex curved surfaces. In terms of applications, successful implementations are demonstrated in aerospace structural monitoring, building vibration detection, human motion capture, and closed-loop control of soft robotics. Finally, we discuss current challenges and propose future research directions. Owing to its exceptional material compatibility and conformal printing capabilities, DIW technology is poised to become a critical tool for enhancing flight safety and extending equipment service life.