The jasmonate family comprises lipid-derived oxidation compounds (oxylipins), which function as plant hormones to regulate diverse developmental processes and defense responses. The pleiotropic effects of jasmonates are ascribed to a variety of biologically active derivatives synthesized along different branches in the octadecanoic pathway. Jasmonate biosynthesis occurs in the first round of the signaling pathway, which is initiated by certain external signal molecules or developmental cues connected to the release of fatty acid precursors from membrane lipids. Newly synthesized jasmonate molecules then mediate the second round of that pathway, inducing the expression of related genes. In particular, certain jasmonates produced in a localized site along their biosynthetic pathway act as a long-distance signal that transmits to distal parts of the plant, eliciting an immune response against a broad spectrum of pathogens and herbivores. The jasmonate-signaling pathway is connected to other signaling pathways associated with various phytohormones, all constituting a complex regulatory network linked to ubiquitin/proteasome-mediated protein degradation of repressors that negatively regulate transcription. In this review article, we highlight the pioneering research conducted on signaling pathways for the biosynthesis and action of jasmonates.