In this study, a series of novel Isoquinolinone derivatives were synthesized as potential multi-target antipsychotics. Among these, compound 13 showed high affinity for dopamine D and serotonin 5-HT, 5-HT, 5-HT, and 5-HT receptors, showed low affinity for off-target receptors (5-HT, H, and α), and negligible effects on ether-a-gogo-related gene (hERG; i.e., reduced QT interval prolongation). An animal behavioral study revealed that compound 13 reversed APO-induced hyperlocomotion, MK-801-induced hyperactivity, and DOI-induced head twitch. Moreover, compound 13 exhibited a high threshold for acute toxicity, a lack of tendency to induce catalepsy, and did not cause prolactin secretion or weight gain when compared to risperidone. Furthermore, in the forced swim test, tail suspension test, and novel object recognition test, treatment with compound 13 resulted in improvements in depression and cognitive impairment. In addition, compound 13 had a favorable pharmacokinetic profile in rats. Thus, the antipsychotic drug-like effects of compound 13 indicate that it may be useful for developing a novel class of drugs for the treatment of schizophrenia.