He was first elected to the Canadian House of Commons in the 1963 federal election. After re-election in the 1965 election, he served as parliamentary secretary - first to Prime Minister Lester B. Pearson (1965) and then to Minister of Finance Mitchell Sharp (1966). Pearson later appointed him junior finance minister. He was appointed Minister of National Revenue in 1968 by Prime Minister Pierre Trudeau.
After Trudeau announced his retirement in early 1984 as Liberal Party leader and Prime Minister, Chrétien sought the leadership of the Liberal Party of Canada. The experience was a hard one for Chrétien, as many of his longtime Cabinet allies supported the Turner campaign. He was thought to be a dark horse until the end, but lost on the second ballot to John Turner at the leadership convention that June. Iona Campagnolo would ominously introduce Chrétien as, "Second on the ballot, but first in our hearts."
In the October 1993 election, Jean Chrétien became Prime Minister of Canada by leading his party to a majority victory, ousting Prime Minister Kim Campbell and the Progressive Conservative Party of Canada. The election featured a controversy when the Tories played an ad that was widely seen as mocking his face.
He was re-elected in the 1997 and 2000 elections, all majority governments. This has made him one of the few Canadian Prime Ministers to serve three back-to-back terms and one of the even fewer to have consecutive majority governments.
While Brian Mulroney, Joe Clark, and Pierre Trudeau had all been relative political outsiders prior to becoming prime minister, Chrétien had over 30 years of experience within the government. This experience gave him a masterful knowledge of the Canadian Parliamentary system, and allowed Chrétien to establish a very centralized government that, although highly efficient, was also lambasted by critics as being a "friendly dictatorship" and intolerant of internal dissent.
Chrétien inherited a nation deeply in debt, and one that was close to financial insolvency. With his Finance Minister, Paul Martin, the government began a program of deep cuts to provincial transfers and other areas of government finance. During his tenure as Prime Minister a $42 billion deficit was eliminated, five consecutive budget surpluses were recorded, $36 billion in debt was paid down, and taxes were cut by $100 billion (cumulatively) over 5 years, the largest tax cut in Canadian history. There were, however, undeniable costs associated with this endeavour. The cuts would result in fewer government services, most noticeably in the health care sector, as major reductions in federal funding to the provinces meant significant cuts in service delivery. Moreover, the across the board cuts affected the operations and achievement of the mandate of most federal departments. Many of the cuts would be restored in later years of Chrétien's period in office.
Under Chrétien, Canada did not support the US-led 2003 invasion of Iraq. His reasoning was that the war lacked UN Security Council sanction; while not a member of the Security Council, Canada nevertheless attempted to build a consensus for a resolution authorizing the use of force after a short (two to three month) extension to UN weapon inspections in Iraq. (Critics also noted that, while in opposition, he had also opposed the first US-led Gulf War.) Although criticism from right-wing opposition was vocal, the move proved popular with the Canadian public in general. In December of 2003, it emerged that Chrétien's government had prepared plans for Canada to send as many as 800 Canadian troops to Iraq if the UN Security Council had authorized it; however, a UN request for an increased deployment of Canadian peacekeepers to Afghanistan removed this option from the table. This led some of Chrétien's anti-war critics on the left to accuse the Prime Minister of never really being fully opposed to the war. Nonetheless, Canada was the first non-member of the US-led coalition to provide significant financial aid to the post-war reconstruction effort, relative to Canada's size. This move allowed Canadian companies to bid on reconstruction contracts.