In 2020, infant mortality in the United Kingdom was below four deaths per 1000 live births. Since 2000, the infant mortality rate in the UK has steadily decreased almost year-on-year. The infant mortality rate is an indicator used for several reasons, one of them is health assessment, providing an insight into the overall healthcare system. Other reasons include public health policy, quality of life, and global comparisons.

In 2021, the infant mortality rate in the United Kingdom was four deaths one year per 1,000 live births, one of the lowest infant mortality rate in this period. Infant mortality has fallen considerably since 1900, when there were 150 infant deaths per 1,000 live births.