Volunteering benefits individuals and society but is hard to sustain, especially in emergencies. Based on the volunteer process model and self-determination theory, this study identified the optimal number of motivations and positive experiences profiles and investigated these profiles’ relationships with volunteers’ sustained volunteering during the COVID-19 pandemic. Seven hundred and eighteen volunteers completed a series of measures about motivations to volunteer (e.g., autonomous and controlled), positive experiences (e.g., satisfaction, meaningfulness and happiness) and sustained volunteering. Results indicated that meaningfulness and happiness positively predicted sustained volunteering but satisfaction did not. Furthermore, we identified four distinct groups using latent profile analysis: the highest autonomy-best experience group (34.96%), high autonomy-well experience group (44.84%), moderate autonomy-general experience group (17.83%) and low autonomy-bad experience group (2.37%). Volunteers in the highest autonomy-best experience group showed the highest level of sustained volunteering compared to those in other groups. These findings suggest that volunteers’ motivations and positive experiences play a combined role in sustained volunteering. They also have significance for fostering long-term volunteering. Please refer to the Supplementary Material section to find this article’s Community and Social Impact Statement.