Background: Breast cancer is considered the most common cancer that affects women all around the world. Objective: Our study was designed to measure the level of awareness of breast cancer among women in Saudi Arabia. Methods: Our study is a cross-sectional one. Participants were invited to fill online questionnaires written in the Arabic language and selected randomly from different cities in Saudi Arabia. Results: The majority of the participants (96%) in the study were Saudi women, 27.6% between 16-24 years, 63.3% had a diploma/university degree, 84.7% knew the fact that breast cancer is the most common cancer among females, 51.6% thought females under 30 could not develop breast cancer, 71.9% knew how to perform the examination, 55.1% knew that the best time for breast self-examination was after menstruation, 75.4% were familiar with the signs of breast cancer, especially in nipple related changes, 9.5% were aware that the chance of recovery from breast cancer was very high if detected early, 75.4% believed that family history of breast cancer might be a risk factor, 75.4% knew the influence of hormone replacement therapy in increasing the risk of the disease, 73.8% knew the relation between eating fat and fewer vegetables and increase of the risk of breast cancer, 71% believed that using oral contraceptives would not increase the risk of having breast cancer, and 36.1% of women knew that radiation exposure could increase the risk of breast cancer. Conclusion: This study offers evidence of the need to improve awareness about breast cancer because of the inadequate knowledge about it. More resources desire to increase awareness and offer an aimed level of knowledge about breast cancer in the Saudi females' population.