Aims and background: Urinary retention induced by antipsychotics is commonly observed with low-potency first-generation antipsychotics but is rarely seen with second-generation antipsychotics (SGAs). Aripiprazole, known for its lower incidence of adverse effects, is rarely associated with urinary retention. This case report highlights aripiprazole's potential impact on bladder function and the need for close monitoring after initiation. Case description: An 18-year-old student with moderate depression experienced no improvement on initial treatment with mirtazapine and escitalopram at maximum tolerable dose and adequate time. Following this, the diagnosis was changed to treatment-resistant depression. To enhance the treatment response, aripiprazole 5 mg was added to the medication regimen. Within 1 week, the patient's mood showed significant improvement. However, the patient developed urinary retention, which prompted further investigation. Comprehensive neurological and urological examinations were conducted to exclude any organic causes for the urinary retention. Bladder ultrasound revealed a postvoid residual volume of 250 mL, but the patient did not require catheterization. Consequently, switching to olanzapine 2.5 mg resolved the urinary retention, suggesting aripiprazole as the cause. Conclusion: The resolution of symptoms upon discontinuation of aripiprazole indicates that it likely caused urinary retention. This may be due to its anticholinergic effects, weak H1 receptor antagonism, and α-1-adrenergic receptor blockade. Clinical significance: Aripiprazole-induced urinary retention is a clinically significant adverse effect, although it is relatively uncommon. It highlights the need for careful monitoring of urinary function in patients prescribed aripiprazole, especially those with predisposing factors for urinary retention. Early detection and management are crucial to prevent complications such as bladder dysfunction and kidney damage. This case underscores the importance of considering medication side effects in the differential diagnosis and adjusting treatment plans accordingly to ensure patient safety and comfort.