Alexander served as a local Perth and Kinross Councillor for 18 years, during which time he spent 8 years as Group Leader and Opposition Leader of the Council.
Alexander was elected to the Scottish Parliament in 2016 for the Mid Scotland and Fife region and served as Shadow Minister for Local Government, International Relations and Migration, followed by some time as Deputy Chief Whip of the Party at Holyrood when Jackson Carlaw MSP was Leader. He was then re-appointed as Shadow Minister for Local Government, a post he held until the end of Session 5.
He was re-elected to the Scottish Parliament in 2021 and is now serving as Shadow Minister for Equalities and Older People.
Alexander was appointed a Member of the Order of the British Empire MBE in the Queen's New Year Honours List in 2016.