ABSTRACT This study reveals the impact of the COVID-19 lockdown on self-reported social isolation in a group of hearing-impaired New Zealanders aged 65 years and over. An online questionnaire based on the modified Medical Outcomes Study Social Support Survey (mMOS-SS) was administered as an adjunct to an ongoing hearing aid trial (the CogniAid Trial) from May to June 2020. Total mMOS-SS and subscale scores (instrumental and emotional support) referring to both before and following COVID-19 lockdown (March to June 2020) were compared. A total of 135 participants from the CogniAid Trial were invited through emails to participate in this online survey; four mails failed to deliver. Among 131 participants, 76 responded, and 46 completed the survey, yielding a response rate of 30%. Twenty-six per cent of the participants reported decreased total and emotional support scores following the lockdown, and about 18% reported a decreased instrumental support score. Generalized linear factorial models for ordinary logistic regression revealed that older age was a significant predictor of decreased instrumental support score [adjusted OR: 1.15 (1.00–1.32)] after controlling for age, gender, duration of hearing problem, current hearing aid use, living arrangement, and physical activity status. No significant association was found between COVID-19 lockdown on social support status and gender, ethnicity, education level, having paid work, unpaid or volunteer work and depression status; however, an association was found between the lockdown and both marital status and living arrangement amongst a group of older New Zealanders.