Introduction A chronically discharging modified radical mastoid cavity may require surgical intervention. We aim to explore two techniques. Objective To compare outcomes of subtotal petrosectomy (STP) and canal wall reconstruction with bony obliteration technique (CWR-BOT). Study Design Retrospective cohort study. Setting A tertiary referral center. Patients All patients with a chronically discharging mastoid cavity surgically treated at the Radboud University Medical Center by STP or CWR-BOT in 2015 to 2020, excluding patients with preoperative cholesteatoma. Main Outcome Measures Dry ear rate, audiometry, and rehabilitation. Secondary Outcome measures Healing time, number of postoperative visits, complications, cholesteatoma, and need for revision surgeries. Results Thirty-four (58%) patients underwent STP, and 25 (42%) CWR-BOT. A dry ear was established in 100% of patients (STP) and 87% (CWR-BOT). The air–bone gap (ABG) increased by 12 dB in STP, and decreased by 11 dB in CWR-BOT. Postoperative ABG of CWR-BOT patients was better when preoperative computed tomography imaging showed aerated middle ear aeration. ABG improvement was higher when ossicular chain reconstruction took place. Mean follow-up time was 32.5 months (STP) versus 40.5 months (CWR-BOT). Healing time was 1.2 months (STP) versus 4.1 months (CWR-BOT). The number of postoperative visits was 2.5 (STP) versus 5 (CWR-BOT). Cholesteatoma was found in 15% (STP) versus 4% (CWR-BOT) of patients. Complication rate was 18% (STP) and 24% (CWR-BOT) with a need for revision in 21% (STP) and 8% (CWR-BOT), including revisions for cholesteatoma. Conclusion STP and CWR-BOT are excellent treatment options for obtaining a dry ear in patients with a chronically discharging mastoid cavity. This article outlines essential contributing factors in counseling patients when opting for one or the other. Magnetic resonance imaging with diffusion-weighted imaging follow-up should be conducted at 3 and 5 years postoperatively.