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To develop effective insecticides against Lepidoptera pests, 25 novel <i>N</i>-pyridylpyrazole derivatives containing thiazole moiety were designed and synthesized based on the intermediate derivatization method (IDM). The insecticidal activities of these target compounds against <i>Plutella xylostella</i> (<i>P. xylostella</i>), <i>Spodoptera exigua</i> (<i>S. exigua</i>), and <i>Spodoptera frugiperda</i> (<i>S. frugiperda</i>) were evaluated. Bioassays indicated that compound 7g−7j exhibited good insecticidal activities. Compound 7g showed especially excellent insecticidal activities against <i>P. xylostella</i>, <i>S. exigua</i>, and <i>S. frugiperda</i> with LC₅₀ values of 5.32 mg/L, 6.75 mg/L, and 7.64 mg/L, respectively, which were adequate for that of commercial insecticide indoxacarb. A preliminary structure-activity relationship analysis showed that the insecticidal activities of thiazole amides were better than that of thiazole esters, and the amides with electron-withdrawing groups on the benzene ring were better than the ones with electron-donating groups. This work provides important information for designing novel <i>N</i>-pyridylpyrazole thiazole candidate compounds and suggests that the 7g is a promising insecticide lead for further studies.