Objective: To explore the effects of community building environment and sports with fitness APP usage and their interactions on teachers exercise habits in the Yangtze River Delta Region, so as to provide a scientific basis for the development of a sports and health promotion intervention program for teachers. Methods: A total of 2 530 in service teachers from four provinces and cities in the Yangtze River Delta region, namely, Shanghai, Zhejiang, Jiangsu and Anhui Province, were sampled in May-June 2023 by using convenient cluster random sampling method. Self designed questionnaire was used to collect the basic information of the surveyed teachers, Physical Activity Building Environment Evaluation Questionnaire and the Sports with Fitness APP Usage Questionnaire were used to measure the teachers subjective perception of the community building environment and the usage of sports with fitness APP, respectively. Physical Exercise Habituation Scale was used to assess the level of exercise habits. Logistic regression models were applied to analyze the effects of community building environment and sports with fitness APP usage on physical exercise, and the interaction effects were analyzed by using additive and multiplicative models. Results: Among all the teachers surveyed, 658 of them reported good physical exercise habits (26.0%), and differences in the rate of physical activity habit formation by gender, age, years of teaching, as well as subject of teaching were statistically significant ( χ 2=42.94, 39.73, 35.47, 218.23 , P <0.05). Teachers with physical exercise habits had significantly higher community building environment scores and sports and fitness APP use than teachers without exercise habits ( t =12.17,16.54, P <0.05). Adjusting for the confounders of age, gender, years of teaching experience, and subjects taught, multifactorial unconditional Logistic regression analysis showed that the probability of teachers having good physical exercise habits increased by 22% for every 1-point increase in the community building environment score on average ( OR =1.22, 95% CI =1.11-1.40), and the probability of teachers having good physical exercise habits increased by 16% for every 1-point increase in the sports with fitness APP score on average ( OR = 1.16 , 95% CI =1.03-1.31) ( P <0.05). Interaction analyses showed that there was an additive interaction between the effects of community building environment and sports and fitness APP use on teachers physical exercise habits after adjustment, and the 95% CI for RERI , API and SI were 1.17 -1.65, 0.12-0.46 and 1.78-3.33 ( P <0.05), respectively, and there was no multiplicative interaction ( P >0.05). Conclusions The community building environment and the usage of sports & fitness APP show impacts in the formation of teachers physical exercise habits in the Yangtze River Delta region, and there is an interaction effect. Enhancing the construction of smart sports centers around the community can provide a high quality external environment for the physical exercise habits formation.