<p>Scalable printing of stretchable conjugated polymer films offers the opportunity to develop low-cost and large-area wearable electronics. However, achieving optimal film morphology to simultaneously improve energy dissipation and charge transport is still challenging for printed conjugated polymer films. Herein, we fabricate large-area stretchable conjugated polymer films with low crystallinity but strong chain alignment toward a high-performance wearable X-ray detector by simultaneously regulating fluid field and solidification dynamics during bar-coating. The strong fluid field aligns conjugated polymer chains in the coating direction and enhances solution aggregation in the initial wet layer, while sequential rapid solidification of the thin wet layer further restricts polymer crystallization but facilitates the alignment of aggregates, forming highly-aligned nanofiber networks within the elastomer phase. The elastomer-constrained nanofiber networks can further align with strain to maintain connectivity, providing an efficient charge transport channel during stretching. Consequently, the film shows high charge mobilities of 6.11 and 2.98 cm² V⁻¹ s⁻¹ under 0% and 100% strains, among the highest values for stretchable conjugated polymer films. The designed film also exhibits a high sensitivity of 1757.2 µC Gy_air⁻¹ cm⁻² and an ultralow detection limit of 72.5 nGy_air s⁻¹, maintaining good X-ray imaging capability before and after stretching.</p>