Background There is a paucity of data on public awareness of cancer in Ethiopia. This study assessed cancer signs, symptoms, and risk factors awareness among individuals aged 18 and older in Addis Ababa, Ethiopia. Method A population-based face-to-face interview was conducted applying a validated cancer awareness measure (CAM) tool. A total of 600 adults (315 males and 285 females) were recruited using a multistage sampling technique. One open-ended and ten closed-ended questions were used to assess awareness of cancer signs and symptoms. To assess awareness of cancer risk factors, one open-ended and twelve closed-ended questions were used. Logistic regression analysis was used to test the association between sociodemographic status and awareness of cancer signs, symptoms, and risk factors. Results Based on the responses for the open-ended questions, unexplained bleeding (23.16%) and smoking (24.17%) were the most frequently recalled cancer sign and risk factor, respectively. Based on the responses for the closed questions, the majority of respondents identified tiredness all the time (80.7%) as a cancer symptom and alcohol use (82.5%) as a cancer risk factor. The odds of cancer signs and symptoms awareness was higher in those with primary (AOR = 4.50, 95% CI, 1.72–11.79, p = 0.02), secondary (AOR = 4.62; 95% CI 1.86–11.43; p = 0.001), and tertiary (AOR = 7.51; 95% CI 3.04–18.56; p < 0.001) education than those who were illiterate. The odds of awareness about cancer signs and risk factors was 0.28 (95% CI 0.12–0.65; p = 0.003) and 0.22 (95% CI 0.83–0.58; p = 0.002) times lower, respectively, among individuals aged 60 and older than those aged 18 to 29. Conclusions Young adults who attended formal education of primary or higher level may have a better cancer signs and symptoms awareness. Future education interventions to increase awareness of the society in Addis Ababa may target illiterate and the elderly.