Scott was born in Ottawa to a family with extensive political connections. He was educated at St. Michael's College at the University of Toronto. After graduating, he earned a law degree from Osgoode Hall Law School at York University and joined the firm of Cameron, Brewin, Weldon, McCallum and Skells.

In addition to his courtroom work, Scott began teaching civil procedure at the University of Toronto Law School in 1968. In 1974, Scott worked for the Berger Commission, studying the impact of pipeline development on aboriginal Canadians in the Northwest Territories.

Scott first ran for public office in the provincial election of 1981. He chose to run for the Ontario Liberal Party. He lost to Progressive Conservative cabinet minister Margaret Scrivener by 1,022 votes.

Scott was narrowly re-elected in the 1990 election that defeated the Peterson government. He was challenged by former Tory cabinet minister Keith Norton, who had come out of the closet by this point, and ran as an openly gay politician. Scott's sexual orientation was an open secret during his time in politics, but declined to reveal it, and there were concerns in Scott's campaign that Norton would attempt to make an issue of this matter.

Ian Scott was appointed the Attorney General of Ontario under the David Peterson Government. He held that appointment for the five year period from June 26, 1985 to October 1, 1990. However, not only did Ian Scott hold the position of Attorney General, but he was also appointed the Minister responsible for women's issues. His two major responsibilities were to make the laws and to advance women's issues.

In order to effectively deal with women's issues, Scott's staff in the Attorney General's Office had to be hired and trained to work on issues from a feminist perspective. In light of the Ministry's responsibility to serve the public from a feminist perspective, staff in the Attorney General's Office soon became well versed in feminist thinking and ideology.

He came under increasing pressure to come out of the closet, particularly from many of his constituents in St. George-St. David, which includes the Church and Wellesley neighbourhood, home to Canada's largest gay and lesbian community. After his retirement from politics, Scott publicly acknowledged his long term relationship for the first time in 1993, upon the death of his partner Kim Yakabuski.

Scott died in his sleep at his Rosedale home in Toronto, a dozen years after the stroke that left his sharp mind intact but reduced his legendary powers of persuasion to monosyllables.