Introduction Adapting to a child with Autism Spectrum Disorder (ASD) can impact the occupational performance of mothers because of the care they demand, which can lead to difficulties in carrying out their occupations. Objective To investigate the occupational performance and adaptation of mothers to their children with ASD. Method Cross-sectional, descriptive, quantitative and qualitative study conducted with 11 mothers of children with ASD aged 2-9 years. Data were collected using the Parental Disability Adaptation Scale (EPAD) and the Canadian Occupational Performance Measure (COPM). EPAD data were analyzed by adding the scores of each participant and calculating the general average, whereas COPM data were analyzed from the values assigned to performance and satisfaction. Results The mothers were well adapted to their children; however, they evaluated the presence of functional problems for occupational performance after their birth. Functional problems in the productivity category, specifically in work performance due to the demands of caring for the children, were mentioned by most mothers. In the self-care category, some mothers reported problems related to going to the salon and taking a shower. In the leisure category, some mothers indicated problems with reading, physical activity, traveling and/or visiting friends. Conclusion The mothers in this study reported that adapting to their children with ASD involves factors such as transmission of the diagnosis, information, children characteristics, socioeconomic conditions, resilience, and personal beliefs and expectations. In conclusion, the mothers of children with ASD investigated presented functional problems regarding their occupational performance after the birth of these children.