Hypertension is common in autosomal-dominant polycystic kidney disease (ADPKD) but may occasionally reflect a secondary etiology. We report a 71-year-old man with ADPKD and end-stage renal disease who developed persistent, refractory hypertension following renal transplantation despite multidrug therapy and bilateral native nephrectomy. Evaluation revealed an elevated aldosterone-to-renin ratio, and adrenal venous sampling confirmed unilateral aldosterone excess consistent with a left aldosterone-producing adenoma. The patient underwent robotic adrenalectomy with subsequent improvement in blood pressure control and reduced antihypertensive requirements. This case highlights the importance of evaluating for primary hyperaldosteronism in patients with ADPKD and resistant hypertension, even in the setting of advanced renal disease or prior nephrectomy.