Objectives: This study aims to explore parents’ exercise habits (PEH), exercise motivation (EMO), and exercise behavior (EB) in Shanghai junior high school students. Methods: A nationwide online survey was conducted across Shanghai from February to June 2023 using a randomly stratified sampling design. In total, 803 questionnaires were distributed across Shanghai via online platforms. A total of 777 complete and detailed responses were included in the final analysis. Structural equation modeling techniques were employed to analyze the collected data using Smart-PLS 4.0. Results: It has been statistically proven that all the scales used in this inquiry to determine the mean scores, standard deviation, excess kurtosis, and skewness values were reliable and produced satisfactory results except H2 and H3. The results (H1: β=0299, t=4.358, p=0.000; H4: β=0.129, t=2.713, p=0.007; H5: β=-0.198, t=3.502, p=0.000; H6 : β=0.208, t=5.482, p=0.007; H7: β=0.140, t=3.735, p=0.007; H8: β=0.143, t=3.801, p=0.007; H9: β=0.132, t=3.175, p=0.000; H10: β=0.106, t=2.891, p=0.000; H11: β=0.366, t=9.110, p=0.000) supported our hypothetical model and explained that parents’ exercise habits (PEH), social motivation (SMO), ability motivation (AMO), and healthy motivation (HMO) benefits students’ exercise behavior (EB). Although fun motivation (FMO) and appearance motivation (APMO) have no effect on students’ exercise behavior, parents’ exercise habits (PEH) have effect on all types of exercise motivation (EMO). Conclusions: PEH, SMO, AMO, and HMO affect EB in adolescents. The SMO and AMO play mediating roles in the relationship between PEH and EB.