For 1981–1987 she was Deputy Director of the Research Institute for Developing Countries, Warsaw School of Economics.

[3] From 2001 until 2003, Hübner was the Head of Office of the Committee for European Integration and Secretary of State at the Ministry of Foreign Affairs.

[6] In November 2004, Hübner was appointed Commissioner for Regional Policy in the European Commission led by President José Manuel Barroso.

Between 2006 and 2007, Hübner served as member of the Amato Group, a group of high-level European politicians unofficially working on rewriting the Treaty establishing a Constitution for Europe into what became known as the Treaty of Lisbon following its rejection by French and Dutch voters.

On 15 September 2010 she joined the Spinelli Group in the European Parliament, which was founded to reinvigorate the strive for federalisation of the EU; other prominent supporters included Jacques Delors, Daniel Cohn-Bendit, Guy Verhofstadt, Andrew Duff, Elmar Brok.

[12] In November 2017, Hübner joined a parliamentary majority by voting in favor of a resolution invoking Article 7 of the Treaty on European Union, thereby potentially stripping Poland of voting rights in the EU for violating the common values of the bloc, including the rule of law.

[17] Shortly after, her political opponents had pictures of Hübner and five other Polish politicians strung from a makeshift gallows in a public square in Katowice.