Although kinase activators hold significant therapeutic promise, their development remains challenging and rarely achieved. Here, we report the discovery of direct small-molecule activators of p21-activated kinase-1 (PAK1), a key regulator of cardiac homeostasis, using a rational peptide-guided strategy. Targeting PAK1 autoinhibitory regulation, we identified a previously unrecognized autoinhibition-release site between the autoregulatory region and the kinase domain. Subsequent high-throughput screening and medicinal chemistry optimization yielded selective allosteric activators that enhance PAK1 activity with micromolar potency and isoform selectivity. Structural and mechanistic analyses indicate that these activators disrupt autoinhibitory regulation and promote local and global conformational transitions to the active state. Enhanced PAK1 signaling was confirmed in cardiac cells, and in vivo studies demonstrated therapeutic efficacy in both inherited and acquired cardiac hypertrophy. Collectively, these findings establish rational modulation of kinase autoinhibitory regulation as a potential strategy for the broader discovery of kinase activators, a largely unexplored area of therapeutic development.