Employing low‐dimensional perovskite has been proven to be a promising approach to enhance the efficiency and stability of perovskite solar cells. Here, thiopheniformamidine hydrochloride is introduced into CH3NH3PbI3‐based printable mesoscopic perovskite solar cells, to form 1D iodide lead thiophenamidine (TFPbI3) in situ. This judiciously designed low‐dimensional perovskite can effectively passivate the defect of perovskite and induce the perovskite crystals to grow in a direction perpendicular to the substrate. Thus, the obtained 1D@3D perovskite could suppress the charge recombination and promote the charge transfer significantly. Benefiting from its dual effect and robustness, a significantly improved power conversion efficiency of 17.42% is yielded. The authors also develop high‐performance printable mesoscopic perovskite solar cells with a champion efficiency approaching 13% for aperture area about 11.8 cm2, as well as outstanding operational stability, retaining 90% of the original power conversion efficiency after 1000 hours of continuous illumination at the maximum power point in air. The formation of 1D iodide lead thiophenamidine (TFPbI3) in situ in perovskite films not only passivates the defect, but also leads to oriented growth of perovskite crystal. The highly ordered 1D@3D perovskite films exhibit superior intrinsic stability and photophysical properties. Consequently, 1D@3D‐based printable mesoscopic perovskite mini‐modules demonstrate an efficiency approaching 13% with impressive long‐term operational stability.