To investigate the knowledge, attitude, and practice (KAP) of photoaging in the Chinese population. This web-based cross-sectional study was conducted between January 2023 and March 2023 among the Chinese population aged 18–80 years old. Participants’ knowledge, attitude, and practice toward photoaging were collected through a self-administered questionnaire. A total of 830 questionnaires were collected, with 826 valid questionnaires and an efficiency rate of 99.52%. There were 274 (33.17%) males and 532 (64.41%) aged 31–51 years old. The average knowledge, attitude, and practice scores were 7 (4, 9) (possible range 0–12), 31.5 (28, 34) (possible range 8–40), and 33 (24, 42) (possible range 11–55), respectively, indicating poor knowledge, good attitude, and moderate practice. Spearman correlation analysis showed that knowledge was negatively correlated with attitude (r = − 0.111, P < 0.05) and practice (r = − 0.113, P < 0.05), and attitude was positively correlated with practice (r = 0.992, P < 0.05). The multivariable linear regression model showed that for each point increase in attitude score, the practice score increased by 2.96 points (β = 2.96, 95% CI 2.91–3.01, P < 0.001). The Chinese population has poor knowledge, good attitude, and moderate practice toward photoaging. A good attitude toward photoaging would lead to good practice, and more outreach and education for the Chinese population might be needed.