Aims This study investigates the prevalence of cochlear nerve deficiency and associated MRI findings in newborn babies with single sided deafness (SSD) at a tertiary children’s hospital in the greater Auckland region over the last 15 years. Methodology Medical records were reviewed for patients who failed the newborn hearing screening through the New Zealand Universal Newborn Hearing Screening and Early Intervention Programme (UNHSEIP) between April 2010 – October 2025. Patients with SSD confirmed by diagnostic tone burst Auditory Brainstem Response (ABR) testing were included. Magnetic Resonance Imaging (MRI) studies of the internal auditory pathway were reviewed. Approval for data access and exemption of ethics approval was obtained from the local Research and Development office. Results Total of 2796 patients were referred from the screening programme for diagnostic ABR over the last 15 years. Eighty-three (2.97%) patients had unilateral severe to profound SNHL (44 right sided, 39 left sided), with a male to female ratio of 1:1.24. MRI scans were performed on 74 patients, of whom 59 (79.7%) had cochlear nerve aplasia (can) and 6 (8.1%) had cochlear nerve hypoplasia (CNH). MRI was successfully conducted with feed and wrap technique in 23 patients. Among the CNA patients, 24 had a normal ipsilateral inner ear on MRI, 15 had an associated hypoplastic internal auditory canal, 6 had an enlarged vestibule, 5 had absent vestibular nerves. Seven CNA patients had an underlying genetic syndrome. Eleven patients had normal MRI findings. The median age at the time of MRI was 6 months. The most common ethnicities were New Zealand European 26.5%, Chinese 24.1%, Māori 9.64%, and Indian 9.64%. Conclusion Structural abnormalities were found to cause 79.5% of the unilateral severe to profound hearing losses in the Auckland population. Early MRI scans avoided the need for a general anaesthetic and allowed for early diagnosis and helped clinicians to counsel and manage patients and their families appropriately.