Abstract Scalable ambient fabrication of perovskite solar modules is often limited by film non‐uniformity, particularly in the widely used dimethylformamide–N‐methyl‐2‐pyrrolidone (DMF‐NMP) solvent system, where strong formamidine (FA + )‐solvent hydrogen bonding drives local supersaturation and burst nucleation. Here, a molecular additive, 1,2,4‐triazole‐3‐carboxamide (TZC) is introduced, that homogenizes precursor solutions by precisely regulating coordination and crystallization dynamics. The rigid triazole ring and primary amide group in TZC form strong bidentate chelation with Pb 2+ , stabilizing coordination against the inherently weaker monodentate solvent binding. Meanwhile, the amide N‐H groups act as potent hydrogen‐bond donors, engaging with halide anions and solvent molecules in direct competition with FA + , thereby weakening FA + solvation and redistributing the hydrogen‐bond network from FA + ‐solvent cages to TZC‐centered complexes. This increases FA⁺ mobility, suppresses local concentration gradients, and promotes uniform crystal growth. Incorporating TZC yields uniform, highly crystalline perovskite films and enables the fabrication of high‐efficiency ambient‐processed modules with photo current efficiency (PCEs) of 20.3% (15 cm 2 ) and 19.4% (75.8 cm 2 ), along with enhanced moisture resistance and long‐term stability.