The 36-year-old ethnic Albanian, who was recently questioned by the UN war crimes tribunal, dismissed the idea of a possible indictment and pledged to prepare the UN-administered province for what he called the great challenge of its future.
The 120-seat parliament on Friday voted 72 votes to three for Haradinaj to head the new Kosovo government, but members of the second-biggest party, the Democratic Party of Kosovo, led by another former rebel leader, abstained.
Kosovo's Serbs and Serbia's politicians consider him the most notorious rebel leader in Kosovo and have repeatedly insisted that he be indicted.
Haradinaj said the possibility of a war crimes indictment against him was just speculation.
"I consider that there is no case against me," said Haradinaj, shortly before his election.
UN official reaction
Soren Jessen-Petersen, the top UN official in Kosovo, congratulated Haradinaj and Ibrahim Rugova, re-elected president at the same session, and called on them to make Kosovo "a better place for all its inhabitants".
UN official Soren Jessen-Petersen
Formation of the new government follows a coalition deal struck nearly two weeks ago between Rugova's Democratic League of Kosovo and the much smaller Alliance for the Future of Kosovo, led by Haradinaj, which came in third.
Rugova's party won 45% of the vote in the 23 October general elections, but failed to gain the absolute majority needed to govern alone in this disputed province. The smaller Alliance garnered 8%.
Kosovo has been administered by the United Nations since June 1999, after a Nato air war that halted a crackdown by Serb forces on independence-seeking ethnic Albanians.
Haradinaj came to prominence while commanding the rebels of the Kosovo Liberation Army in western Kosovo during that war.
"I have met my obligation toward my country (then) and I promise that all my life I will do the same if my country needs me"
Serbian authorities reportedly have provided evidence to the UN tribunal of Haradinaj's responsibility for alleged crimes against the Serb civilians in western Kosovo during the province's war.
But Haradinaj said: "I have met my obligation toward my country (then) and I promise that all my life I will do the same if my country needs me."
The chief UN war crimes prosecutor, Carla del Ponte, has said she will file an indictment against a senior ethnic Albanian rebel by the year's end. She did not say who that will be.