Rehn takes over from Spaniard Joaquin Almunia, who will become competition commissioner in the 27-country bloc's executive. France's Michel Barnier was named internal market commissioner, with responsibility for financial services.
The formation of the European Commission is the latest stage in the EU's efforts to maintain its influence on the world stage after the economic crisis.
The 27-person team, which represents almost 500 million people, is likely to take office early next year. It will serve for five years, but first needs the European Parliament's approval.
"In five years' time, I want this Commission to have been instrumental in leading Europe out of the economic crisis towards a competitive economy that provides sustainable growth," Barroso told a news conference.
The nomination of the Commission, a powerful regulatory body, follows the naming of a new EU president and foreign policy chief as well as ratification of the Lisbon Treaty, intended to make EU decision-making smoother (EurActiv 20/11/09).
Almunia, a 61-year-old socialist, gained a reputation for independence and fiscal prudence as economic and monetary affairs commissioner. Rehn, 46, oversaw the accession of Romania and Bulgaria as EU enlargement commissioner.
"Both men are [among] Commission President Barroso's top lieutenants and they are seen as safe pairs of hands," an EU diplomat said.
"In making these appointments, Barroso keeps tight control on two top jobs and keeps Paris, Berlin and London's hands off them."
Europe's economy has started to recover after the global crisis. The EU faces a decision on when to stop emergency financial measures that were used to prop up the economy, and needs to tackle soaring budget deficits.
As competition commissioner, taking over from Neelie Kroes of the Netherlands, Almunia will be asked to enforce strict rules on state aid, prevent protectionism and uphold the EU's single market.
The appointments in full:
- José Manuel Barroso (Portugal): President
- Joaquin Almunia (Spain): Competition
- Catherine Ashton (UK): Foreign Affairs High Representative
- Michel Barnier (France): Internal Market and Services
- Olli Rehn (Finland): Economic and Monetary Affairs
- Dacian Ciolos (Romania): Agriculture
- John Dalli (Malta): Health and Consumer Policy
- Karel De Gucht (Belgium): Trade
- Stefan Füle (Czech Republic): Enlargement
- Connie Hedegaard (Denmark): Climate Action
- Maire Geoghegan-Quinn (Ireland): Research and Innovation
- Janusz Lewandowski (Poland): Budget/Financial Programming
- Guenther Oettinger (Germany): Energy
- Janez Potocnik (Slovenia): Environment
- Neelie Kroes (Netherlands): Digital Agenda
- László Andor (Hungary): Employment, Social Affairs and Inclusion
- Maria Damanaki (Greece): Maritime Affairs and Fisheries
- Johannes Hahn (Austria): Regional Policy
- Rumiana Jeleva (Bulgaria): International Cooperation, Humanitarian Aid and Crisis Response
- Siim Kallas (Estonia): Transport
- Cecilia Malmström (Sweden): Home Affairs
- Andris Piebalgs (Latvia): Development
- Viviane Reding (Luxembourg): Justice, Fundamental Rights and Citizenship
- Algirdas Šemeta (Lithuania): Taxation and Customs Union
- Antonio Tajani (Italy): Industry and Entrepreneurship
- Androulla Vassiliou (Cyprus): Education, Culture, Multilingualism and Youth
- Maros Sefcovic (Slovakia): Interinstitutional Relations and Administration
(EurActiv with Reuters.)