The WHO Guidelines on risk reduction of cognitive decline and dementia provide evidence-based recommendations on lifestyle behaviours and interventions to delay or prevent cognitive decline and dementia. Worldwide, around 50 million people have dementia and, with one new case every three seconds, the number of people with dementia is set to triple by 2050. The increasing numbers of people with dementia, its significant social and economic impact and lack of curative treatment, make it imperative for countries to focus on reducing modifiable risk factors for dementia. Action area 3 of the Global action plan on the public health response to dementia 2017–2025 is risk reduction. These WHO Guidelines are an important tool for health care providers as well as governments, policy-makers and other stakeholders to strengthen their response to the dementia challenge.