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The control of chilling injury in peach fruit by a new regulator network, that exogenous γ-aminobutyric acid (GABA) regulates the metabolisms of polyamines (PAs), the GABA shunt, and proline, is still unclear. This study found that GABA induced an increase in the expression of <i>PpADC</i> and <i>PpODC</i> and a decrease in the expression of <i>PpPAO</i> expression, resulting in the accumulation of PAs. There was also an increase in the expression of <i>PpGAD</i>, which improved GABA content, and an increase in the expression of <i>PpP5CS</i> and <i>PpOAT</i>, which improved proline content. The correlation analysis showed that an increase in <i>PpADC</i>/<i>PpP5CS</i> expression was closely associated with the accumulation of putrescine and that the synergistic increase in the expression of <i>PpODC</i> and <i>PpGAD</i>/<i>PpP5CS</i>/<i>PpOAT</i> was closely related to the accumulation of spermine, proline, and GABA induced by GABA. Importantly, arginine and <i>PpADC</i> played a key role in putrescine accumulation, whereas ornithine and <i>PpODC</i>/<i>PpOAT</i> played a crucial role in the synergistic accumulation of spermine, proline, and GABA induced by GABA. This study provides new information on GABA-induced cold tolerance in peach fruit.