This study assessed the level of public knowledge regarding ionizing radiation, the sources of information available to the public, and the preferred sources of education. A descriptive cross-sectional study was conducted in Jeddah, Saudi Arabia. A 15-question survey was distributed to participants who attended a radiation awareness activity held for the public. Participants were asked to rank their confidence regarding ionizing radiation knowledge on a Likert-style scale. They also answered questions on their perception of risks, the source from which they received health information, and their preferred method of education. Only 3% of the 244 participants were “knowledgeable” about ionizing radiation. Nine percent stated they were confident about their ionizing radiation knowledge, and they were more knowledgeable than unconfident individuals (p = 0.041). Age, gender, and education level played no role in ionizing radiation knowledge (p = 0.746, p = 0.245, and p = 0.060, respectively). Among those who had undergone a medical imaging investigation during the past year, only 24% received an explanation of the risks and benefits. Participants overestimated the risk of nuclear plants, as this was selected as the source with the greatest risk to health, followed by medical sources. Most of those who had prior knowledge searched for the information on the internet (34%), however, more participants would prefer to receive education from their healthcare providers (36%).