A novel method for synthesizing 1,5-disubstituted tetrazole derivatives via blue light-promoted N–H insertion of aryldiazoacetates into NH-tetrazoles is presented. The reaction affords mixtures of regioisomeric products, with a predominance of 1,5-disubstituted derivatives. A comprehensive investigation of reaction conditions and substrate effects influencing regioselectivity has been performed. These findings provide new insights into the regioselectivity of NH-tetrazole alkylation and reveal potential applications of this approach in the assembly of tetrazole-containing scaffolds.