Fully conjugated ladder polymers (CLPs) have emerged as promising candidates for next-generation organic electronics due to their extended π-conjugation pathways, intrinsic charge transport anisotropy, and exceptional chemical and thermal stability. However, insolubility remains a critical bottleneck, primarily stemming from side reactions that disrupt the linear structure. Herein, we report a soluble CLP, benzo[a]benzo[5,6][1,4]thiazino[3,2-