He served in the cabinet of Margaret Thatcher as Secretary of State for the Environment from 1979, then as Defence Secretary from 1983 to 1986, when he resigned over the bitter dispute over Westland Helicopters known as the Westland crisis.
He challenged Thatcher for the leadership of the Conservative Party in November 1990, but the contest - which Douglas Hurd also entered - was eventually won by John Major. He returned to government as Secretary of State for the Environment (with particular responsibility for replacing the poll tax), later as President of the Board of Trade and then Deputy Prime Minister. He was also an early key enthusiast for the Millennium Dome.
In December 2002 Heseltine controversially called for Iain Duncan Smith to be replaced as leader of the Conservatives by the "dream-ticket" of Kenneth Clarke as leader and Michael Portillo as deputy. He suggested the party's MPs vote on the matter, rather than party members as currently required by party rules. Without the replacement of Duncan Smith, the party has not "a ghost of a chance of winning the next election", he said.
In his business life he founded Haymarket, which publishes many popular magazines.