- In 1640 the gymnasium operating was turned into the Royal Academy of Turku., The book collection of the gymnasium, comprising approximately 20 volumes, served as the starting point of the Library of the Royal Academy of Turku.
- In 1707, a letter from the Royal Chancellery ordered printing houses in Sweden to provide the universities in the empire with one copy of each publication.
- After 1809, Finland became an autonomous part of the Russian empire and from 1820 to 1917 the library was provided with deposit copies of publications published in Russia.
- In 1828, the university was moved to Helsinki and it started operating under the name of the “Imperial Alexander University”.
- In 1832, the university building designed by the architect Carl Ludvig Engel was inaugurated while the new library building north of the university building was inaugurated in 1845.
- In 1879–1881, the library building was renovated under the supervision of the architect Frans Sjöström.
- In 1893, electrical lighting was installed in the library, allowing its opening hours to be prolonged. The new large reading room with reference library was opened.
- In 1906, the library facilities grew considerably, when the annex, Rotunda, designed by Gustaf Nyström was completed.
- By the year of Finnish independence, 1917, the library’s collection had grown to as large as 300,000 volumes.
- By the 1950s, the library facilities had become insufficient. Based on a design by Aarne Ervi, repository facilities were excavated under the Porthania building.
- In 1977–1985, the library building was renovated under the supervision of the architect Olof Hansson.
- From 1982, the library has also received statutory deposit copies of audio recordings. The growing collection of sheet music manuscripts supplements the audio materials.
- In the mid-1990s the entire Seepra quarter was dedicated to the library, when the Faculty of Pharmacy moved to Viikki; the library quarter was inaugurated in 1998.
- In 1998–2000, Rotunda was renovated under supervision from LPR Architects Oy.
- In 2000, the new underground book cave was inaugurated.
- In 2005, the library building’s ownership was transferred from the state to the University of Helsinki's' funds.
- In 2006, the name of the library was changed to the National Library of Finland with an amendment of the Universities Act.
- In 2011–2012, the façade of the main building was renovated.
- In 2013–2015, Rotunda’s facade was renovated and the extensive renovation of the library main building was implemented, both under supervision of LPR Architects Oy. The historic library building of the National Library of Finland on Unioninkatu reopened to the public on 1st March 2016.
More about the history of the National Library of Finland: Knapas, Rainer (2012): Tiedon valtakunnassa (Helsingin yliopiston kirjasto Kansalliskirjasto 1640–2010), In the kingdom of knowledge. Helsinki University Library the National Library of Finland 1640–2010.