McCausland made his political debut in the 1982 Assembly elections, standing in North Belfast for the United Ulster Unionist Party (UUUP), when he was eliminated early on in the count.

[6] Disenchanted with the UUP under David Trimble, whom he had supported for the leadership, he defected to the Democratic Unionist Party in 2001 and was re-elected as a local councillor for the Oldpark area in 2001 and 2005.

He was suspended twice from the Assembly for unparliamentary language[8] in respect of allegations of Provisional IRA membership made against the Sinn Féin president Gerry Adams.

In response to McCausland's letter, Richard Dawkins, an evolutionary biologist and noted atheist, said "If the museum was to go down that road then perhaps they should bring in the stork theory of where babies come from.

[12] A Spotlight investigation into Red Sky, a Belfast-based company, showed financial irregularities which was just awarded a new maintenance contract by the Northern Ireland Housing Executive (NIHE).

McCausland, along with other members of the DUP, intervened and he made a formal request as Minister for Social Development to the NIHE board to extend Red Sky's contract.

McCausland's then-special adviser, Stephen Brimstone, was alleged to have called a DUP councillor, Jenny Palmer, to "pressure her" into changing her vote at the NIHE meeting to overturn the board's decision to cancel Red Sky's contract.

In January 2021, McCausland faced calls to resign from the Education Authority after sharing an article on Facebook about Becket Cook, an American who lived as a gay man until he became a born-again Christian.

[16] McCausland adheres to the pseudoarchaeological belief that the people of the British Isles are descended from the lost tribes of Israel,[17] and has addressed events organised by the British-Israel-World Federation.