Background <p>Lung cancer is the leading cause of cancer deaths worldwide. Due to late detection, patients have low survival rates. We aimed to examine lung cancer epidemiology in the Kingdom of Saudi Arabia by computing standardised rates for the different regions of the country and across years.</p> Methods <p>We used the Saudi Cancer Registry data to conduct a retrospective study for all lung cancer cases diagnosed between 2015 and 2020. We identified cases using ICD-O-3 codes, with no exclusions by morphology. We followed the Surveillance, Epidemiology, and End Results guidelines for staging. We analysed demographic and tumour characteristics and used mid-year population estimates from the General Authority for Statistics for standardisation. We then calculated age-sex standardised incidence rates and standardised incidence ratios using indirect standardisation. We compared geographical trends in incidence across regions and years.</p> Results <p>Based on the total number of 3,861 lung cancer cases reported to the Saudi Cancer Registry between 2015 and 2020, we estimated the average six-year crude incidence rate of 2.1 per 100,000. We observed variability in incidence across different regions ranging from 0.59 per 100,000 in Jazan to 3.36 per 100,000 in the Eastern Province. Age-standardised rates show males with consistently higher rates than females throughout the study period. Sex-based differences were statistically significant (<i>P</i> &lt; 0.05). We also found that males had a higher proportion of squamous cell and small cell carcinomas than females (18.71% vs. 08.99% and 10.22% vs. 05.13% respectively).</p> Conclusions <p>Our findings show a male predominance, regional disparities, and late-stage adenocarcinoma diagnoses. These patterns are consistent with known risk factors, including tobacco exposure, environmental risks, and delayed detection, and support the implementation of targeted prevention, earlier diagnosis, and regionally tailored interventions in the Kingdom of Saudi Arabia.</p>