Mutations in PTEN-induced kinase 1 (PINK1) contribute to autosomal recessive Parkinson’s disease with cognitive and neuropsychiatric comorbidities. Disturbances in dendritic and spine architecture are hallmarks of neurodegenerative and neuropsychiatric conditions, but little is known of the impact of PINK1 on these structures. We utilized Pink1-/- mice to study the role of endogenous PINK1 in regulating dendritic architecture, spine density and spine maturation. Pink1-/- cortical neurons of unknown sex showed decreased dendritic arborization, affecting both apical and basal arbors. Dendritic simplification in Pink1-/- neurons was primarily driven by diminished branching with smaller effects on branch lengths. Pink1-/- neurons showed reduced spine density with a shift in morphology to favor filopodia at the expense of mushroom spines. Electrophysiology revealed significant reductions in miniature excitatory postsynaptic current (mEPSC) frequency in Pink1-/- neurons, consistent with the observation of decrea...