When a guardian is diagnosed with cancer, the emotional and psychological toll they endure can have a profound impact on their children’s mental health. Understanding the factors that contribute to heightened anxiety in these children is crucial for identifying mental health disorders early. This cross-sectional study explored the relationship between having a guardian with cancer and elevated anxiety levels in adolescents, accounting for confounding variables such as sex, age, and socioeconomic status. Data were obtained from the 2022 National Health Interview Survey (NHIS) using the Sample Adult Interview (27,651 participants) and Sample Child Interview (7464 participants) datasets. The independent variable (guardian’s cancer diagnosis) was derived from the Sample Adult Interview, while the dependent variable (childhood anxiety) and confounders were derived from the Sample Child Interview. Using Stata 16.0, the datasets were merged based on household index variables, yielding a final sample of 4563 participants. Logistic regression analyses assessed the correlation between a guardian’s cancer diagnosis and anxiety levels in children. The results show that children with a guardian battling cancer are significantly more likely to develop anxiety (through the use of odds ratio), with the effect size varying based on factors such as sex, income, and environment. Girls, children from lower-income families, and those with a guardian experiencing depression were at particularly high risk. These findings highlight the strong link between familial health challenges and adolescent anxiety, emphasizing the need for early intervention and mental health support in families affected by cancer.