This study is aimed to evaluate the cancer risk among patients with coal workers' pneumoconiosis (CWP) using a nationwide population-based dataset. Patients without previous cancer who had been diagnosed with CWP and followed-up for more than 1 year between 1997 and 2006 were recruited from the Taiwan National Health Insurance database. Standardized incidence ratios (SIRs) of cancers in CWP patients were calculated and compared to the cancer incidence in the general population. Risk factors for cancer development were also analyzed. After a median follow-up of 9.68 years, 954 cancers developed among 8,051 recruited CWP patients, with a follow-up of 69,398 person-years. The SIR for all cancers was 1.12 [95% confidence interval (CI) 1.04–1.18]. Males older than 80 years had a SIR of 1.27 (95% CI: 1.06–1.51). The SIRs of esophageal (1.76, 95% CI: 1.24–2.44), gastric (1.42, 95% CI: 1.13–1.76), liver and biliary tract (1.18, 95% CI: 1.01–1.37) and lung and mediastinal (1.45, 95% CI: 1.26–1.66) cancers were significantly higher in the CWP group than in the general population. Multivariate analysis showed that age ≥ 60 years [hazard ratio (HR) 1.70, 95% CI: 1.41–2.05), male gender (HR = 1.79, 95% CI: 1.44–2.23) and liver cirrhosis (HR = 3.99, 95% CI: 2.89–5.51) were significant predictors of cancer development in patients with CWP. We concluded that patients with CWP, especially elderly males, were at increased risk of cancer. Age, male gender and liver cirrhosis were independent risk factors for cancer development.