1793

• 7 March 1793
  Peter Friedrich Ludwig, Grand Duke of Oldenburg (pictured below), establishes a seminar for teacher training (Lehrerseminar) according to a plan drawn up by General Superintendent Esdras Heinrich Mutzenbecher.
  
  Peter I Friedrich Ludwig, Grand Duke of Oldenburg  (1755 – 1829)

1920

• 26 March 1920
  The teacher training seminar becomes an institution of higher education and in 1926 its courses are replaced by two-year teacher training courses which continue until the outbreak of war in 1939.
  
  The teacher training college building completed in 1846

1945

• 1 October 1945
  The newly founded Pedagogical Academy (Pädagogische Akademie) in Oldenburg (renamed the Pedagogical College Oldenburg in 1948) becomes the first teacher training institution to reopen its doors in post-war Germany.

1959

• 23 February 1959
  The Council of the City of Oldenburg calls on the government of Lower Saxony and the Lower Saxony State Parliament to establish a second regional university in Oldenburg.

1970

• 25 August 1970
  The government of Lower Saxony passes a resolution on the establishment of universities in Oldenburg and Osnabrück.

1971

• 1 March 1971 
  A founding committee is appointed in Oldenburg, one third of the members of which are professors, one third research fellows and one third students.
  
  A panel discussion with members of the founding committee

1972

• 26 April 1972
  The Universitätsgesellschaft Oldenburg e.V. is established.

1973

• 5 December 1973
  The Lower Saxony State Parliament resolution of 3 December 1973 on the founding of the Universities of Oldenburg and Osnabrück and the integration of the teacher training colleges comes into force. Study activities commence in April 1974 with eight "Diplom" degree courses and a pilot programme for single-phase teacher training.

1974

• 29 May 1974
  The University Council unanimously adopts the constitutional order drawn up by the University’s founding committee and votes to name the university after the German journalist and pacifist Carl von Ossietzky, but the government of Lower Saxony rejects the name.
  
  Student protest: Students affix the name to the wall of a university building
• 17 December 1974
  A cooperation agreement is signed between the University of Oldenburg and the Lower Saxony branch of the German Trade Union Confederation (DGB), the first agreement of its kind in the Federal Republic of Germany.

1980

• 17 April 1980
  The University signs its first cooperation agreement with a foreign university, the University of Groningen.
  
  Jan Bleumink (University of Groningen) and Hans-Dietrich Raapke (University of Oldenburg) sign the cooperation agreement.
• 18 December 1980
  The ground is broken for the construction of the Energy Laboratory, a symbol for the focus research area "alternative energy sources".
  
  The Oldenburg Energy Laboratory, which covers its own energy requirements

1985

• 22 October 1985
  Launch of the Computing Science degree programme with 55 students.

1989

• 1 January 1989
  The government of Lower Saxony gives the green light for the expansion of marine research in Founding of the Federal Institute for Culture and History of the Germans in Eastern Europe (BKGE) in Oldenburg, which becomes an affiliated institute in 2000.
• 30 May 1989
  The government of Lower Saxony gives the green light for the expansion of marine research in Oldenburg and the founding of the Institute for Chemistry and Biology of the Marine Environment (ICBM).
  
  Lower Saxony Science Minister Johann-Tönjes Cassens and Lower Saxony Minister President Ernst Albrecht at the ICBM stand

1990

• 12 December 1990
  Joint declaration by the Universities of Oldenburg and Bremen on the coordinated expansion of research and teaching activities and the creation of a "North-West science region".

1991

• 3 October 1991
  Ceremony at which the University is officially named after Carl von Ossietzky, attended by Gerhard Schröder, then Minister President of Lower Saxony.
  
  Official naming ceremony: Gerhard Schröder with Rosalinde von Ossietzky-Palm, daughter of Carl von Ossietzky

1992

• 29 January 1992
  Inauguration of the OFFIS Institute for Information Technology as an affiliated institute.

1996

• 8 February 1996
  Founding of the Hörzentrum as an affiliated institute specialised in hearing research, followed five years later by the establishment of the Hörtech Center of Competence as a non-profit organisation.
  
  The House of Hearing (Haus des Hörens) in Oldenburg

1997

• 13 October 1997
  Opening of the Hanse-Wissenschaftskolleg Institute for Advanced Study (HWK) in Delmenhorst as a joint institution of the Universities of Oldenburg and Bremen. 
  
  A research institute that attracts renowned scientists from all over the world: the HWK

2001

• 14 November 2001 
  Founding of the Center for Distributed Learning (later renamed the Center for Lifelong Learning – C3L), which combines continuing education courses and e-learning projects.

2002

• 16 October 2002
  Launch of the Hanse Law School, a joint project of the University of Oldenburg, the University of Groningen and the University of Bremen.

2003

• 1 August 2003
  Opening of the ForWind Center for Wind Energy Research, a joint institute of the Universities of Oldenburg and Hannover (and since 2009 also of the University of Bremen).

2004

• 18 October 2004
  The University becomes one of the first in Germany to convert to Bachelor's and Master's degrees

2008

• 28 February 2008
  Oldenburg wins the competition to be awarded the title "City of Science 2009".
  
  The City of Science programme booklet

2009

• 13 August 2009
  Inauguration of the NEXT ENERGY – EWE Research Center for Energy Technology as an affiliated institute.

2012

• 15 June 2012
  The University of Oldenburg's Cluster of Excellence application "Hearing4all" is selected for the German Excellence Initiative. Its partners in the project are the Hannover Medical School (MHH) and the Leibniz University Hannover.
• 10 August 2012
  Establishment of the School of Medicine and Health Sciences as the University's sixth faculty after an amendment to the Lower Saxony Higher Education Act (NHG) creates the legal framework for the European Medical School Oldenburg-Groningen (EMS).
• 23 October 2012
  Inauguration of the European Medical School Oldenburg-Groningen (EMS). Lower Saxony Minister President David McAllister welcomes the first 40 medical students.
• 28 November 2012
  Oldenburg hearing researchers Prof. Dr. Dr. Birger Kollmeier, Prof. Dr. Volker Hohmann and Dr. Torsten Niederdränk (Siemens AG) win the prestigious German Future Prize for science and innovation.

2013

• 7 September 2013
  The Karl Jaspers House opens in Oldenburg's Dobbenviertel district. The villa houses the private library collection of the Oldenburg-born psychiatrist and philosopher, as well as the German Karl Jaspers Society and the EWE Foundation.
  
  The Karl Jaspers House in Oldenburg’s Dobbenviertel district

2014

• 26 May 2014
  The Dutch royal couple King Willem-Alexander and Queen Máxima visit the University. An energy symposium is held in their honour, ending with a joint final declaration by 40 experts in which the expansion of renewable energies is defined as a decentralised and cross-border task.
• 17 November 2014
  The research vessel Sonne is officially handed over to its home institute, the University of Oldenburg's Institute for Chemistry and Biology of the Marine Environment (ICBM).

2015

• 18 September 2015
  The University is awarded a new EU-funded Centre of Excellence: the Jean Monnet Centre of Excellence "Europeanising Coastal Regions".

2017

• 31 May 2017
  Opening of the Helmholtz Institute for Functional Marine Biodiversity (HIFMB) at the University of Oldenburg, which combines the University's research excellence with that of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) in Bremerhaven.
• 13 November 2017
  The Prize Papers Project become part of the German Academies' Programme, which is funded by the German federal and state governments. Oldenburg historian Prof. Dr. Dagmar Freist leads the international collaborative research project.
•  

2018

• 31 May 2018
  The EWE research institute NEXT ENERGY (a University-affiliated institute) is relaunched as the Institute of Networked Energy Systems of the German Aerospace Center (DLR).
• 27 September 2018
  Excellence Strategy: The Cluster of Excellence "Hearing4all" secures funding for another seven years.
• 14 Dezember 2018
  The Lower Saxony State Parliament votes to expand University Medicine Oldenburg and double the number of places on its medical degree programme from 40 to 80 in the 2019/20 winter semester.

2019

• 1 April 2019
  Oldenburg University research groups from the fields of computer science and marine sciences start working at the new DFKI Laboratory Lower Saxony established by the German Research Centre for Artificial Intelligence (DFKI).
• 15 July 2019
  In its assessment, the German Science and Humanities Council (WR) describes the human medicine pilot degree programme at the European Medical School Oldenburg-Groningen (EMS) as an "impressive course" and calls on the state to continue its expansion.
• 11 November 2019
  The state approves funding for eight additional digitalisation professorships at the University of Oldenburg and the Jade University of Applied Sciences.

2020

• 1 July 2020
  Launch of the "Startup Region Northwest" programme after the University of Oldenburg once again secures a top position in the nationwide EXIST university-based business start-ups competition.
• 30 September 2020
  Lower Saxony politicians pledge 80 million euros for the construction of a teaching and research building for University Medicine Oldenburg – a victory for the University, Oldenburg hospitals and numerous other stakeholders in Oldenburg and the surrounding region who had resisted Lower Saxony government plans against the financing of the building.
• 29 October 2020
  The Universities of Oldenburg and Groningen hold an online ceremony to mark 40 years of intense cooperation. The cooperation agreement is renewed for another ten years.

2021

• 15 April 2021
  The University of Oldenburg's Presidential Board and the Board of the University of Groningen adopt a Roadmap for Cooperation 2020–2030 encompassing seven focus areas.

2022

• 13 May 2022
  Inauguration of the research building of the Centre for Marine Sensor Technology (ZfMarS) in Wilhelmshaven. The new building is located next to the ICBM headquarters on Schleusenstraße.
• 14 November 2022
  The University of Oldenburg and Nelson Mandela University in Gqeberha (formerly Port Elizabeth), South Africa, celebrate 25 years of close cooperation.

2023

• 16 February 2023
  The University of Oldenburg participates in the nationwide diversity audit procedure "Shaping Diversity" initiated by the Stifterverband and receives the Shaping Diversity certificate.