Willoch graduated as an economist (cand. oecon.) from the University of Oslo. He served in the Norwegian Brigade that formed part of the Allied occupation in Schleswig-Holstein, Germany, after World War II, and became a dedicated friend of Germany during that time.
He speaks Norwegian, English, German and French, and has published a number of books.
An economist (characterized in 1981 as being "supply side" ) by education and profession, Willoch made an early mark in national politics on issues related to economic development. He expressed deep skepticism about social democratic reforms throughout most of the post-World War II era and has advocated a larger role for market mechanisms to solve economic problems.
Within the Conservative Party, Willoch was respected for his command of the issues and consistent ideological platform. In spite of friendly rivalry with Erling Norvik, Rolf Presthus, and Jan P. Syse, these and other party members led a political shift in Norway away from the social democratic legacy.
Willoch's first political post was as a member of the Oslo City Council from 1952 to 1959.
He was appointed as minister of trade in the short-lived but notable John Lyng cabinet from August to September 1963, following the Kings Bay Affair that brought to an end the uninterrupted Einar Gerhardsen cabinets since World War II.
He was appointed to the same ministerial post in the government of Per Borten in 1965-1970. He stepped down from this post to become first the Parliamentary leader, and then chairman of the Conservative Party 1970-1974.
In 1973, he unified his party in opposition to the newly introduced restrictions on use of land. This formed a watershed in Norwegian politics, in that the party adopted a stronger ideological alternative to the social democratic establishment that had dominated post-World War II politics. Some historians, notably Francis Sejersted attribute this in large part to the Norwegian Labour Party's exuberant continuation of social democratic efforts.
Willoch served as the leader of the Foreign Affairs committee in the coalition government and from then until he retired from parliament in 1989.
As a member of the Borten government he faced the constitutional question of the marriage of the then Crown Prince Harald to a commoner, Sonja Haraldsen. (They married in 1968 and since 1991 have been king and queen). Willoch is reported to have never considered opposing the union.
Most of Willoch's political career was spent in opposition to various Labour governments. His rhetorical style was characterized by conservative use of language and carefully articulated viewpoints that many considered cold or even sarcastic. His debates with long-time adversary Gro Harlem Brundtland became legendary in Norway and were by several accounts based on personal as well as political differences. Brundtland wrote in her memoirs that she learned from Willoch "how not to treat people, or parties."
Willoch was asked to form a Conservative party government when a non-socialist coalition gained a majority in the parliamentary elections of 1981. The cabinet depended on the support of the Christian Democrats and Centre Party, and in 1983 these joined the cabinet to become a coalition government.
By the parliamentary elections of 1985, Willoch's cabinet had lost much of its parliamentary basis and was dependent on the Progress party for support. The cabinet lost a vote of no-confidence over Willoch's proposal to increase surcharges on gasoline, when the Socialist Left Party, Labour Party, and Progress party joined forces. A minority government led by Gro Harlem Brundtland took over through the rest of the parliamentary period.
In spite of difficult parliamentary conditions, the Willoch cabinet embarked on a series of reforms that to many seemed like reversals of long-standing social democratic reforms, and to others changes that reflected new and emerging economic realities.
Often cited changes include:
The Willoch government's foreign policy was largely consistent with those of prior Labour party cabinets in terms of Norwegian commitments under the NATO treaty, but deviated sharply on the issue of non-proliferation. Where the Labour Party promoted a reduction of tensions in the Nordic region, the Willoch cabinet approved forward logistical bases for American rapid deployment forces and lent full support to the NATO double track decision of 1979
Willoch came under criticism for not acting sooner to stop the activities of politician and career diplomat Arne Treholt, who was arrested in 1984 and convicted of treason and espionage in favor of the Soviet Union and Iraq.
Willoch earned a reputation as a sharp-witted, sometimes acerbic politician. During his years in parliament and in various governments, he was respected by his political allies and opponents alike, but never gained the popularity of other prime ministers in his time in office.
Willoch served as county governor (fylkesmann) of Oslo and Akershus from 1989 to 1998. From 1998 to 2000 he was chairman of NRK, the Norwegian Broadcasting Corporation. He was also director of the Nansen Institute. Since 1986, he has been deputy chairman of the International Democrat Union (IDU), and he has been President of the Deutsch-Norwegische Gesellschaft (German-Norwegian Society).
Considered one of the most pronounced conservative Norwegian politicians in his time, he has in later years shifted his position in many areas. He has taken issue with the "culture of greed" , "tax paradises' , the environment and has been particularly harsh in his condemnation of Israel's policies toward Palestinians. He has accused the country of "ethnic cleansing," and he says it is "creating terror" by cultivating extremism "as if in a greenhouse in the Palestinian areas" This has prompted his long-time friend and party colleague Jo Benkow to comment that "On this topic, Willoch must be the most partisan public person in this country." He has also claimed that, though "there are strong reasons to warn against the new antisemitism", it will not strengthen Israel's cause to accuse critics of Israeli politics of antisemitism He also claims that Israel indirectly contributes to New antisemitism stating that "It would be naive to ignore that Israel's politics towards the Palestinians has become a new source of negative attitudes." In May of 2006, Willoch invited Atef Adwan, an official in Hamas to a private luncheon at Det Norske Selskab, commenting that "A dialogue with Hamas is very useful." an action that prompted criticism by fellow Conservative party member and former foreign minister Jan Petersen
Kåre Willoch has attended the Bilderberg meetings.