The modern-day borough of Knowsley was formerly composed of villages and towns in Lancashire dating back to 650 AD.

Knowsley experienced rapid population expansion in the 1950s and 1960s, resulting from the combination of industrialization and migration, including a significant amount of overspill development from Liverpool.

[7] Record house building and strong growth in inward investment yielded the borough's first small rise in population in over 25 years in 1995.

[11] The new district was awarded borough status from its creation, allowing the chairman of the council to take the title of mayor.

The Metropolitan Borough of Knowsley is one of the six constituent local government districts of the Liverpool City Region.

The combined authority has effectively become the top-tier administrative body for the local governance of the city region and the leader of Knowsley Council, along with the five other leaders from neighbouring local government districts, take strategic decisions over economic development, transport, employment and skills, tourism, culture, housing and physical infrastructure.

According to the 2011 census, 80.9% of people in Knowsley describe themselves as Christian, the highest proportion in any local authority in England and Wales.