Background: Helicobacter pylori (H. pylori), an important human pathogen, is classified as a human carcinogen. It is known to cause dyspepsia, peptic ulcers, and gastric cancer. Awareness regarding H. pylori infections in Saudi Arabia awaits investigation to reduce or even eliminate the infection that would ease the substantial burden of managing H. pylori among both malignant and non-malignant diseases. Aims: The study aims were to (1) assess the knowledge of H. pylori infection, testing, and management among undergraduate students in Saudi Arabia and (2) compare the H. pylori knowledge among health science and non-health science students. Methods: This study involved a cross-sectional online survey among 334 undergraduate students in health science and non-health science colleges at King Saud University, Saudi Arabia, using a valid and reliable author-developed survey. The survey had two sections: the socio-demographic factors and knowledge items regarding H. pylori. Data were collected during the 2019–2020 academic year. Data analysis included descriptive statistics, Chi-square, and Mann–Whitney U test. The knowledge scores were categorized as poor, fair, and good. Results: Less than 10% of the students in both groups had a good knowledge level about H. pylori. The comparison of the overall mean between both groups was non-significant. Moreover, the level of knowledge of the respondents was significantly associated with their university level (p < 0.001), family monthly income (p < 0.007), having heard about H. pylori infection (p < 000.1), and a previous history of H. pylori infection (p < 000.1). Conclusion: The overall knowledge level of Saudi undergraduate students about H. pylori infection was low. Thus, health awareness interventions through educational programs are recommended for improving their knowledge about H. pylori infection and its prevention.