Elections to Knowsley Metropolitan Borough Council were held on 3 May 2012. One third of the council was up for election, with councillors elected at the 2008 Knowsley Council election defending their seats this time.
Due to the 'in thirds' system of election, changes in vote share are compared to the corresponding 2008 elections and calculated on that basis. After the election, Labour gained total control of the council, wiping out every Liberal Democrat councillor.