This chapter discusses about the green synthesis of various nanomaterials by plants, biomolecules, and microorganisms for the application in pesticides recognition. Plants parts mediate the synthesis of metal nanoparticles by producing phytochemicals which act as natural reducing and capping agents. Neem, aloe-vera, green tea, tulsi, hibiscus, lemon peel, pomegranate peel, etc., are the popular plants used for nanoparticle synthesis via green route. This chapter also discusses about the synthesis of nanomaterials like metal, metal oxides, metal sulfides, chalcogenides, etc., facilitated by bacteria and fungi for application in detection of harmful pesticides. Many biomolecules like enzymes, proteins, NADH, DNA, aptamers, etc., are reported for synthesis of nanomaterials which have shown the remarkable recognition of pesticides. The scope of this chapter is to discusses the role of plants, biomolecules, microorganisms, and algae/sea weeds toward synthesis of variety of nanomaterials and their application in the biosensing of pesticides like thiram, malathion, glycophosphate, triazophos, etc.