INTRODUCTION: Precarious employment has emerged as a public health concern. This study explored the association between precarious employment and unmet healthcare needs and participation in health checkups. METHODS: This study analyzed data from a nationally representative sample of 12,215 wage workers, comprising a total of 65,405 observations, obtained from the Korean Welfare Panel Study (2008-2022). Precarious employment was characterized by insecure employment, inadequate wages, and lack of worker rights, and categorized into quartiles: lowest, low, high, and highest. The study focused on two outcomes: unmet healthcare needs due to financial constraints and nonparticipation in health checkups over the past year. Robust Poisson regression models were used to calculate prevalence ratios and 95% CIs under the framework of generalized estimating equations. RESULTS: Of the respondents, 0.7% reported unmet healthcare needs, while 44.2% did not attend health checkups. Compared with workers in the lowest precarious employment quartile, those in the high and highest precarious employment quartiles had a 5.83-fold (95% CI=2.73, 12.45) and 12.53-fold (95% CI=5.88, 26.70) increase in the prevalence of experiencing unmet healthcare needs, respectively. Similarly, compared to the lowest precarious employment quartile, those in the high and highest precarious employment quartiles had a 2.38-fold (95% CI=2.26, 2.51) and 2.92-fold (95% CI=2.77, 3.08) increase in the prevalence of nonparticipation in health checkups, respectively. CONCLUSIONS: Precarious employment is associated with unmet healthcare needs and nonparticipation in health checkups. This study underscores the need for policies that improve healthcare access for workers in precarious conditions.