The diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae) is one of the most destructive pests of cruciferous crops worldwide, with management complicated by its rapid development of resistance to synthetic insecticides. Botanical extracts offer an eco-friendly alternative for pest management and the choice of extraction solvent can strongly influence the bioactivity of the resulting extract. In the present study, extracts of six botanicals viz., Azadirachta indica, Nerium oleander, Plumeria rubra, Solanum grandiflora, Swietenia macrophylla and Tagetes erecta were prepared in three solvents of differing polarity (methanol, ethyl acetate and hexane) and evaluated for their effect on larval weight gain of P. xylostella over a 5–12 day feeding period, alongside solvent check and untreated check controls. Across all three solvent systems, larvae in the treated groups consistently showed lower weight gain than those in the solvent check and untreated check, with the treated check recording the least weight gain throughout the observation period. Among the botanicals, extracts of T. erecta, S. grandiflora and S. macrophylla were associated with comparatively greater suppression of larval weight gain than A. indica, N. oleander and P. rubra. Solvent polarity also influenced efficacy with methanol and ethyl acetate extracts generally producing stronger growth-suppressive effects than hexane extracts. These findings suggest that polar and semi-polar solvent extracts of selected botanicals hold promise as components of an integrated, eco-friendly management strategy for DBM.