The first public library in Prague opened on 1st July 1891 and followed on from the activity of federal libraries in the 2nd half of the 19th century. The “Public General Library of the Royal Capital Prague” was established by the decree of the city council as a library intended for all citizens of Prague. At the beginning it had 3370 books used in the lending library and reading room. The first site of the library was on the street Na Zderaze in the New Town, it moved several times, and only in 1903 did it find a permanent site on the corner of Platnéřská Street and Mariánské Square in the Old Town, i.e., where its current building is. From 1898 to 1920 its director was the librarian and famous poet Antonín Sova, who used his knowledge of German and American librarianship, started to build a system of catalogues, founded the first six branches and attempted to ensure that the library gained a "dignified building in the centre of the city”.
The law combining Prague and another 38 towns and municipalities which created „Greater Prague“ came into force on 1st January 1922. As soon as this happened, the town council approved a proposal for the combining of the libraries of these municipalities and the creation of a unified and fully centralised "Municipal Library of Prague”. The library network consisted of the Central Library and another 40 libraries on the territory of the city. It contained approximately 260 thousand volumes, and there were almost 700 thousand lendings per year. The system of signatures and catalogues was unified, and the purchase of library stock was centralised. Gradually other libraries opened, and in 1938 the library operated on 50 sites in Prague (there were 640 thousand volumes, and approximately 2 million lendings). Dr. Jan Thon, who was the library director from 1920 to 1942 and 1945 to 1948 played a significant role in the development of the library.
The previous building of the Central Library was no longer fit for the needs of the all-Prague library network. This long-term and serious problem was finally resolved as a result of the Prague Municipal Insurance Company, the resources of which were used to build the new building on Mariánské Square from 1925 to 1928. This was the first purpose-built library building in Czechoslovakia and also one of the most modern in Europe. It was designed on a scale for a broad range of library activities and also for concert, educational and exhibition activities. The extensive storage facilities with modern design allowed the dynamic growth of the library stock. The scale of the implemented project is shown by the fact that until the mid 1970s the building was wholly suitable for the needs of the rapidly growing network. In addition to the lending library, study room, newspaper reading room, children’s lending library and reading room, a music department was also included in the new building (Bedřich Smetana Library, founded in 1921), and also gradually a library for the blind (in the years 1932–1948), a professional library of city administration and Suk Library of writing for youth, in 1942 a theatre and film department was created.
During the Nazi occupation the activities of the library stagnated, thousands of books considered by the Nazis to be racially, politically and ideologically harmful were removed, and several library workers were imprisoned. In 1945 the normal activities of the library were resumed and the removed books were returned. But not for long. After 1948 all of the library's activities became subject to totalitarian ideology, and there was considerable organisational chaos. Some works were removed and destroyed, and many qualified workers were subject to personal persecution.
In the second half of the 1950s there was a gradual renewal of the expert level of the library, and the 1960s witnessed a perceptible development of library and educational services and also a significant ideological relaxation of their content. In 1966 the Municipal Library of Prague was the co-organiser of the Prague symposium concerning metropolitan libraries and one of the initiators for the creation of INTAMEL (International Association of Metropolitan Libraries). In 1968 the library subscribed to the demands of the so-called Prague Spring with its action programme. In the sixties 12 new branches were opened, and other specialised departments were set up (for example, Pragensia study room, several departments for youth). The “Peoples’ Library of Science, Technology and Art” was founded dealing with educational and cultural-education activities which gained considerable popularity for the library in the relatively favourable atmosphere of the time.
The so-called “normalisation” of the 1970s once again brought powerful ideological pressure, the creation of new “libri prohibiti”, the complete halting of international cooperation and an overall stagnation of the library. From the end of the 1970s there was a gradual internal renewal of the work of the library and the professional aspect began to predominate over the ideological one. But of course the external restrictions persisted, so only with the revolution of 1989 was there a return to the standard status of the library in a democratic society.
In the 1980s there was a significant modernisation of the branches, many new libraries were opened and their network was rationalised. The types of items held by the library were expanded to include, in particular, audio media. In 1982 computers began to be used in the central records of the inventory and during categorisation.
In the 90s the Municipal Library of Prague optimised the network of its branches, attempted to locate them in suitable municipal buildings and attain the essential standards for their further development in them. In 1995 the Prague City Council approved the intention of the Municipal Library of Prague for a reconstruction of the services of the Central Library on Mariánské Square and decided on the financing of the general reconstruction of its building, which was performed in the years 1996 and 1997. This was not merely a building reconstruction, but it also involved a new concept for services and the complete automation of library work.
On 20April 1998 the Central Library was officially opened, and all the branches were gradually automated in the ten years between 1999 and 2009.
The Great Flood in August 2002 destroyed the branches in Karlín and Holešovice and flooded the basement of the Central Library on Mariánské Square. The operation of the automated library network was renewed over several days thanks to alternative power sources, even though the Central Library itself was closed for four weeks. By May 2003 the destroyed basements of the Central Library were reconstructed. The renewed branch in Holešovice was opened in February 2004, and library services in Karlín have been ensured since 2003 by a mobile library. The collection of valuable printed works damaged in the Holešovice branch was saved, preserved, gradually dried by volunteers and is now gradually being restarted. There has been a gradual development of the possibilities of the automatic system of the Municipal Library of Prague Koniáš , new services have been established (often utilising the possibilities of the internet), there has been an improvement in user comfort, and many branches have gained new premises (Školská, Smíchov, Vršovice, Záhřebská, Spořilov, Dejvice, Hostivař) or their existing ones have been significantly reconstructed and sometimes expanded (Břevnov, Korunní, Opatov, Novodvorská, Holešovice, Ruská, Stodůlky and others). The end of the year 2009 brought a significant change in the borrowing system – possibility of returning any borrowed library unit in any branch of the Municipal Library of Prague network.