Prior evidence suggests that physical activity may reduce the risk of multiple diseases and mortality. However, whether and how physical activity affects the aging process remains largely unexplored. We included 284,479 UK Biobank participants and computed leukocyte telomere length (LTL) deviation (i.e., the difference between genetically determined and observed LTL) and biological age acceleration (BAA, defined as the discrepancy between the phenotypic age of a person and the average phenotypic age in the cohort of individuals with the same age and sex) as the indexes for aging acceleration. Linear and logistic models were used to estimate the associations of self-reported physical activity items and patterns (identified by principal component analysis), as well as accelerometer-assessed physical activity, with aging acceleration. Analyses of physical activity patterns indicated, a higher level of adherence to activity patterns predominated by strenuous sports, other exercises, walking for pleasure, heavy and light housework, and public transportation use was associated with a lower risk of aging acceleration, whereas a higher level of adherence to patterns predominated by job-related activities was associated with a higher risk of aging acceleration. Analysis among 62,418 participants with accelerometer-measured physical activity corroborated these results. Physical activity, such as strenuous sports and other exercises at leisure time and use of public transportation, was associated with a reduced biological aging. Besides highlighting the importance of engaging in physical activity for healthy aging, our results provide further evidence for the beneficial effect of physical activity on the telomere attrition process.© The Author(s) 2023. Published by Oxford University Press on behalf of The Gerontological Society of America.