Objectives: This study aimed to investigate the trends in neoplasm-related hospital admissions (NRHA) in England and Wales between 1999 and 2019. Methods: This is an ecological study using publicly available data taken from the two main medical databases in England and Wales; the Hospital Episode Statistics database in England and the Patient Episode Database in Wales. Hospital admissions data were collected for the period between April 1999 and March 2019. Results: A total of 35,704,781 NRHA were reported during the study period. Females contributed to 50.8% of NRHA. The NRHA rate among males increased by 50.0% [from 26.62 (95% CI 26.55–26.68) in 1999 to 39.93 (95% CI 39.86–40.00) in 2019 per 1000 persons, trend test, p < 0.001]. The NRHA rate among females increased by 44.1% [from 27.25 (95% CI 27.18–27.31) in 1999 to 39.25 (95% CI 39.18–39.32) in 2019 per 1000 persons, trend test, p < 0.001]. Overall, the rate of NRHA rose by 46.2% [from 26.93 (95% CI 26.89–26.98) in 1999 to 39.39 (95% CI 39.34–39.44) in 2019 per 1000 persons, trend test, p < 0.001]. Conclusion: Hospital admission rates due to neoplasms increased between 1999 and 2019. Our study demonstrates a variation in NRHA influenced by age and gender. Further observational studies are needed to identify other factors associated with increased hospital admissions among patients with different types of neoplasms.