In Mexico, paediatric cancer is the leading cause of death for children aged 0-18 years. This study analyses the main challenges for paediatric cancer care from the perspective of three key health systems functions: stewardship, financing and service delivery. The study used a mixed methods approach comprised of: (1) a scoping literature review, (2) an analysis of 2008-18 expenditures on paediatric cancer by the Fund for Protection against Catastrophic Expenditures (FPGC) of Seguro Popular and (3) a nation-wide survey of the supply capacity of 59 Ministry of Health (MoH) and 39 Mexican Institute of Social Security (IMSS) hospitals engaged in paediatric cancer care. The study found that while Mexico has made substantial progress towards universal health coverage (UHC) for paediatric cancer treatment, serious gaps persist. FPGC funds for paediatric cancer increased from 2008 to 2011 to reach US$36 million and then declined to US$13.6 million in 2018, along with the number of covered cases. The distribution of health professionals and paediatric oncology infrastructure is uneven between MoH and IMSS hospitals and across Mexican regions. Both institutions share common barriers for continuous and co-ordinated health care and lack monitoring activities that cripple their capacity to apply uniform standards for high-quality cancer care. In conclusion, achieving universal and effective coverage of paediatric cancer treatment is a critical component of UHC for Mexico. This requires periodic and ongoing assessment of health system performance specific to paediatric cancer to identify gaps and propose strategies for continued investment and improvement of access to care and health outcomes for this important cause of premature mortality.