Objectives: Clean indoor air policies have been an important tool protecting the health of working adults. The purpose of this study was to examine awareness of and support for e-cigarette-free workplace policies among working adults in the United States. Methods: Employees of companies with at least 150 employees (N = 1607, ages 18-65 years) were recruited from an opt-in national panel for an online survey. Results: Nearly half of respondents (48.4%) reported that their employer had a written policy addressing e-cigarette use, 30.2% reported their employer did not have such a policy, and 21.4% reported that they did not know. Most respondents (73.5%) supported e-cigarette-free workplaces, including the majority of current e-cigarette users (53.5%). Multiple regression modeling found that odds of support for e-cigarette workplace policies was significantly higher among never (OR = 1.77, 95% CI: 1.19-2.64) and former e-cigarette users (OR = 1.71, 95% CI: 1.15-2.54) relative to current users. Policy support also varied by perceived harm and other perceptions of workplace vaping, and demographic and workplace characteristics. Conclusions: E-cigarette-free workplace policies have high levels of support among employees, including both current and former e-cigarette users. Policies restricting workplace vaping can improve the health of all employees.