Objective <p>This study investigated the clinical efficacy of personalized 3D-printed modular navigation templates for Femoral Neck System (FNS) implantation in young and middle-aged adults with femoral neck fractures. We evaluated its impact on surgical precision, safety, and radiation exposure.</p> Methods <p>We prospectively enrolled 88 patients with femoral neck fractures, randomly assigning them to either the 3D-FNS group (<i>n</i> = 43), which used personalized 3D-printed navigation templates for FNS guide wire insertion, or the Conventional Freehand FNS group (<i>n</i> = 45). We compared baseline characteristics, operative parameters (time, fluoroscopy, blood loss, guide pin adjustments, incision length), and postoperative outcomes (fracture healing time, Harris Hip Scores (HHS) at 6 months and final follow-up, and complication rates).</p> Results <p>The 3D-FNS group showed significantly reduced operative time, intraoperative fluoroscopy count, intraoperative blood loss, and fewer guide pin adjustments compared to the FNS group (<i>P</i> &lt; 0.05). While incision length was slightly longer in the 3D-FNS group, this was not significant (<i>P</i> &gt; 0.05). The 3D-FNS group also had a significantly shorter fracture healing time and higher 6-month HHS (<i>P</i> &lt; 0.05). Although final follow-up HHS was higher in the 3D-FNS group, the difference was not significant (<i>P</i> &gt; 0.05). Complication rates (femoral neck shortening, femoral head necrosis, nonunion, internal fixation failure) were lower in the 3D-FNS group, but without statistical significance (<i>P</i> &gt; 0.05).</p> Conclusion <p>Personalized 3D-printed modular navigation templates significantly improve the accuracy and safety of FNS implantation, reducing operative time, fracture healing duration, and intraoperative radiation exposure. This offers an innovative and valuable solution for minimally invasive, hip-preserving treatment of femoral neck fractures in young and middle-aged adults.</p>