Purpose: The purpose of this study was to investigate relationships among uncertainty, meaning of life, and anxiety in preoperative cancer patients. Methods: Study participants were 90 adult patients with thyroid, breast, gastric, or colorectal cancer who were admitted to the general surgery ward and daily operation center in a university-affiliated hospital. Data were collected using Mishel’s Uncertainty in Illness Scale, Meaning in Life Questionnaire, and State-Trait Anxiety Inventory. Data were analyzed using t-tests, one-way ANOVAs, Pearson’s correlation coefficient, and a multivariate linear regression analysis (backward stepwise) with SPSS version 24. Results: Anxiety showed a positive correlation with uncertainty in illness (r=.59, p<.001) and a negative correlation with meaning of life (r=-.49, p<.001), and uncertainty had a negative correlation with meaning of life (r=-53, p<.001). The regression model explained 40.0% variance of preoperative cancer patients’ anxiety (F=20.55, p<.001). Significant factors were uncertainty (β=.43, p<.001), meaning of life (β=-.20, p<.001), and low income level (β=.18, p<.001). Conclusion: Our study’s findings show that cancer patients’ anxiety can be reduced within 24 hours before surgery through psychological nursing interventions aimed at reducing uncertainty and improving the meaning of life.