Background: Social media addiction (SMA) caused by excessive dependence on social media is becoming a global problem. At present, most of the SMA studies recruit college students as research participants, with very few studies involving workers and other age groups, especially in China. Objective: This study aims to investigate the current status of SMA among Chinese workers and analyze its influencing factors. Methods: From November 1, 2022, to January 30, 2023, we conducted an anonymous web-based questionnaire survey in mainland China, and a total of 5176 participants completed the questionnaire. The questionnaire included the Social Networking Service Addiction Scale, Maslach Burnout Inventory–General Survey scale, Mindful Attention Awareness Scale, as well as questionnaires regarding participants’ social media use habits and demographic information. Results: Through strict screening, 3468 valid questionnaires were included in this study. The main findings of this study revealed the following: the average SMA score of workers was higher (mean 53.19, SD 12.04), and some of them (393/3468, 11.33%) relied heavily on social media; there were statistically significant differences in SMA scores among workers in different industries (F14,3453=3.98; P<.001); single workers (t3106=8.6; P<.001) and workers in a relationship (t2749=5.67; P<.001) had higher SMA scores than married workers, but some married workers (214/3468, 6.17%) were highly dependent on social media; the level of SMA among female workers was higher than that of male workers (t3466=3.65; P<.001), and the SMA score of workers negatively correlated with age (r=−0.22; P<.001) and positively correlated with education level (r=0.12; P<.001); the frequency of using social media for entertainment during work (r=0.33; P<.001) and the frequency of staying up late using social media (r=0.14; P<.001) were positively correlated with the level of SMA in workers; and the level of SMA in workers was significantly positively correlated with their level of burnout (r=0.35; P<.001), whereas it was significantly negatively correlated with their level of mindfulness (r=−0.55; P<.001). Conclusions: The results of this study suggest that SMA among Chinese workers is relatively serious and that the SMA problem among workers requires more attention from society and academia. In particular, female workers, young workers, unmarried workers, highly educated workers, workers with bad social media habits, workers with high levels of job burnout, and workers with low levels of mindfulness were highly dependent on social media. In addition, occupation is an important influencing factor in SMA. Thus, the government should strengthen the supervision of social media companies. Medical institutions should provide health education on SMA and offer intervention programs for those addicted to social media. Workers should cultivate healthy habits while using social media.