To our knowledge, this is the first epidemiologic study to examine the association between physical activity (PA) and cancer using data from the American College Health Association-National College Health Assessment (ACHA-NCHA). The goal of the study was to understand the dose-response relation between PA and cancer, as well as the associations between meeting US PA guidelines and overall cancer risk in US college students. The ACHA-NCHA provided self-reported information on demographic characteristics, PA, body mass index, smoking status, and overall cancer during 2019–2022 (n = 293,682; 0.08% cancer cases). To illustrate the dose-response relationship, a restricted cubic spline logistic regression analysis was used to evaluate the association of overall cancer with moderate-to-vigorous PA (MVPA) on a continuous basis. Logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals for the associations between meeting the three U.S. PA guidelines and overall cancer risk. The cubic spline observed that MVPA was inversely associated with the odds of overall cancer risk after adjusting for covariates; a one hour/week increase in moderate and vigorous PA was associated with a 1% and 5% reduced overall cancer risk, respectively. Multivariable-adjusted logistic regression analyses showed that meeting the US guidelines for aerobic PA for adults (≥150 minutes/week of moderate aerobic PA or ≥75 minutes of vigorous PA) (OR: 0.85), for PA for adults (≥2 days of muscle strengthening activity in addition to aerobic MVPA) (OR: 0.90), and for highly active adults (≥2 days of muscle strengthening activity and ≥300 minutes/week of aerobic moderate PA or 150 minutes/week of vigorous PA) (OR: 0.89) were statistically significant and inversely associated with cancer risk. MVPA, especially meeting US guidelines, may be inversely associated with overall cancer among college students in the US. To reduce cancer risks, multilevel interventions to promote US physical activity guidelines among college students are warranted.