After graduation, Prunariu started working as a licensed engineer for Industria Aeronautică Română at an aircraft assembly facility.

Having obtained the highest marks during three years of preparation, he was then selected for a joint space flight with the Ukrainian cosmonaut Leonid Popov.

In 2007 he completely retired from the Air Force with the military rank of major general, continuing his professional activity as a civil servant.

Between 1992 and 1993 Prunariu was a Co-leader of the World Bank Project on reorganization of the higher education and research system in Romania.

Between 2006 and 2008 Prunariu accomplished the duties of the Director of the Romanian Office for Science and Technology to the European Commission (ROST) in Brussels.

Prunariu was the main interface in promoting the ASE International Panel's Report Asteroid Threats: A Call For Global Response at the level of the UN COPUOS as a working document for the specialized bodies of this UN Committee.

In 2016, at the 53rd session of UN STS COPUOS, on behalf of the Association of Space Explorers, Prunariu proposed the proclamation by the UN General Assembly of the International Asteroid Day to observe each year at the international level the anniversary of the Tunguska impact over Siberia, Russian Federation, on 30 June 1908 and to raise public awareness about the asteroid impact hazard.

He is the voice of the robot BURN-E in the Romanian dubbed version of the animated film WALL-E made by Disney Pixar.