During his final two university years he taught as a physics teacher and after graduation he worked as a physicist engineer at the Institute of Nuclear Power Reactors in Pitești.

Next he completed an International Relations course at University of Leeds, United Kingdom, under a "Know How Fund" scholarship offered by the Foreign and Commonwealth Office.

In 1999 he received a Doctorate in Law for his thesis entitled "Institutional Reform of the European Union in the Context of the Intergovernmental Conference to Review the Maastricht Treaty".

[7] On 2 July 2022 he started his term as Ambassador extraordinary and plenipotentiary, Permanent Representative of Romania to the Council of Europe in Strasbourg, France.

During his mandate in the United Kingdom, Ambassador Jinga has proven to be an active presence in the British media, emphasising positive accounts about his country and reacting in moments where Romania was blamed.

Ambassador Jinga responded to these allegations through a series of interviews and articles in British newspapers,[10][11] radio and television, presenting his views on the professional value of Romanians and their significant contribution to the UK economy.

[12] When Romania was accused that it was exporting horse meat labelled as beef, Ion Jinga replied in two interviews with the Huffington Post[13] newspaper and Sky News.

[17] Subsequently, the Romanian Ministry of Foreign Affairs released a statement ascribing Jinga's "long pauses and clipped words" to technical difficulties caused by the interviewer's presence in Hong Kong, which led to a delay of several seconds (thus making impossible to say the next phrase prior to hearing the end of the previous one),[18] overlapping voices from a different newsroom and an echo.

[citation needed] Jinga was described soon after his appointment as the Permanent Representative of Romania to the United Nations in New York, as having established himself as an active presence within the UN diplomatic community.

[31] Between 2015 and 2016 he chaired the UN Commission on Social Development and,[32] in October 2016, the President of the UN General Assembly appointed him to the position of Co-Chair of the Intergovernmental Negotiations on the Security Council Reform.

[33] This appointment made Ambassador Jinga the first Romanian (and Eastern European) diplomat to chair this highly sensitive and complicated negotiations process.

[46] Between 1992–1995, 1999–2000, 2002–2003, and in 2013, Jinga taught courses within the field of European integration as an associate professor within the National University of Political Studies and Public Administration in Bucharest.

[49] The book was included in the catalogues of prestigious libraries, such as the Library of Congress, Washington, D.C.; Stanford University Libraries, Stanford, California; Bibilioteca Centrală Universitară 'Eugen Todoran', Timișoara; Biblioteca Centrală Universitară 'Lucian Blaga', Cluj-Napoca,[50] in the references of a number of PhD theses in Romania and the Republic of Moldova,[51] in the European Integration Guide for Professors (the Republic of Moldova), being also cited in the Republic of Moldova's Academy of Sciences' Philosophy, Sociology and Political Sciences Magazine.

Among the book authors in this selection are outstanding personalities of the recent European history, such as Robert Schuman, Jean Monnet, Konrad Adenauer, Charles de Gaulle, Václav Havel, Jacques Delors, Margaret Thatcher, and Romano Prodi.

In analysing the significance of the book, the view of the European Parliament was that "The many honours, decorations and honorary titles Jinga has been awarded throughout his career testify to his exceptional qualities as a diplomat and someone to whom Romania owes recognition since he has represented, and continues to represent, his country's interests in an exemplary manner at crucial times in contemporary European events.

[77] In January 2014, the 'Foreign Policy Romania' magazine named Ambassador Jinga one of the key 100 Romanian personalities who have "moved the country through the power of their ideas or through their own example"[78] in 2013 (he was also mentioned in 2012).

[81][82] In 2021, Ambassador Ion I. Jinga has been awarded the title of Knight Grand Officer of the Royal Order of Francis I, in recognition of his "lifelong commitment to charitable, humanitarian and inter-faith activities in Romania and across the world".