Born and raised in Oslo, Jensen graduated with a degree in business studies from the Norwegian School of Economics.

She chaired the parliamentary Standing Committee on Finance and Economic Affairs from 2001 to 2005, and in 2006 succeeded long-time chairman Carl I. Hagen as leader of the Progress Party.

As she was appointed to the government cabinet in 2013, deputy representative Mazyar Keshvari has met as a regular member in her place.

[9] She played a central role in budget negotiations with the centrist government of Kjell Magne Bondevik, and her work chairing the Finance Committee led her to become increasingly more profiled as a leader-figure within her party.

[7] While many had been speculating about the viability of the party and its future after Hagen resigning, a 2004 survey showed that Jensen enjoyed better general support than him, which was explained by her not being as controversial.

[7] In May 2009, Jensen held a lecture in the House of Commons of the United Kingdom at the invitation of Conservative Party MP Malcolm Rifkind.

Up to one-hundred MP's, business leaders and key persons in British politics was expected to show up at the arrangement.

[13] Ahead of the 2013 election Jensen continued working for a broad centre-right coalition, and endorsed Erna Solberg for Prime Minister.

Although seeing its vote drop significantly, she led the Progress Party into government coalition talks for the first time in its history.

Other reasons cited was that the party been unable to promote their policy in government, and Jensen stated "it’s not worth continuous losses".

Because we fight state monopolies because they don't do good for competition, for price levels, for people's ability to choose between different distributors.

[22] Considering Thatcher "a controversial politician who dared to stand for something," Jensen has expressed support for Thatcherite policies such as "there is no alternative (to market economy)".

She visited the Israeli city of Sderot in the summer of 2008 and experienced Hamas bombing first hand, forcing her and her company to run for the air-raid shelter.

"[22] Jensen has in addition advocated moving the Norwegian embassy in Israel from Tel Aviv to Jerusalem, while also being open to accepting a future recognition of a Palestinian state.

[27] In February 2009, Jensen held a speech where she warned about what she called a "sneaking Islamisation" (snikislamisering) of Norway on the background of a public debate about allowing hijab as part of the police uniform, and demands from Muslim groups of Muslim-only education and special food in prisons.

The statements proved highly controversial in Sweden, and the Progress Party was invited to a tour around Rosengård by the mayor and police chief of Malmö, which it accepted.

She said that she, as a classical liberal, would always fight against totalitarian ideas such as communism and National Socialism, and that radical Islam "is a dark and scary ideology."

[35][36] During the demonstration (a response to newspaper Dagbladet publishing a Muhammad cartoon in the context of a news story) Islamist Mohyeldeen Mohammad had notably "warned" of a "9/11" or "7/7" in Norway to applause from the crowd.