GABAergic dysfunction underlies many neurodevelopmental and psychiatric disorders. GABAergic synapses exhibit several forms of plasticity at both pre- and postsynaptic levels. NMDA receptor (NMDAR)-dependent inhibitory long-term potentiation (iLTP) at GABAergic postsynapses requires an increase in surface GABAARs through promoted exocytosis; however, the regulatory mechanisms and the neuropathological significance remain unclear. Here we report that the autism-related protein PX-RICS is involved in GABAAR transport driven during NMDAR-dependent GABAergic iLTP. Chemically induced iLTP elicited a rapid increase in surface GABAARs in wild-type mouse hippocampal neurons, but not in PX-RICS/RICS-deficient neurons. This increase in surface GABAARs required the PX-RICS/GABARAP/14-3-3 complex, as revealed by gene knockdown and rescue studies. iLTP induced CaMKII-dependent phosphorylation of PX-RICS to promote PX-RICS-14-3-3 assembly. Notably, PX-RICS/RICS-deficient mice showed impaired amygdala-dependent fear learning, which was ameliorated by potentiating GABAergic activity with clonazepam. Our results suggest that PX-RICS-mediated GABAAR trafficking is a key target for GABAergic plasticity and its dysfunction leads to atypical emotional processing underlying autism.