Unique, β-arrestin-biased functionally selective dopamine D2 receptor (D2R) agonist (Ki value 30 nM; EC50 value 50 nM in β-arrestin-2 recruitment assay) that exhibits antipsychotic activity in vivo. UNC9994 markedly inhibited PCP-induced hyperlocomotion in wild-type mice, which effect was completely abolished in β-arrestin-2 knockout mice.