The Library's collection comprises more than 45,000 items and is organised into clearly defined sections, including a Spanish Language Learning Resource Centre, an audiovisual collection, novels, history books, biographies, and works of literature representing the cultures of Spain and Latin America. Most of the collection is published in Spanish, although materials are also available in English, Irish (Gaelic), and the other languages of Spain, namely Catalan, Galician and Basque.

The Library's holdings are organised into the following sections:

• Reference works.
• Spanish and Latin American literature.
• Materials for the teaching and learning of Spanish, Catalan, Galician and Basque.
• History, art and the social sciences.
• Children's and young adult literature.
• English and Irish translations of Spanish and Latin American literature.
• Spanish and Latin American films and documentaries.
• Spanish and Latin American music.
• Cultural journals and magazines.

In addition, the Instituto Cervantes London Library houses the most significant specialist collection on the image of Spain in the travel literature of foreign writers. It spans more than three centuries, covering accounts of Spanish history, society and culture from the early eighteenth century to the present day. Excluding major general libraries, it is difficult to find such a comprehensive collection documenting how Spain has been perceived from different countries, including Great Britain, France, Germany, Italy and the United States.

The Library also holds a unique collection of more than 250 pamphlets published during the Spanish Civil War (1936–1939), reflecting the various political and ideological positions adopted during the conflict. Most of these pamphlets support the Republican cause, although the collection also includes publications sympathetic to Franco and the Catholic Church, as well as strongly anti-communist material. The majority of the pamphlets are in English, with some in Spanish and a small number in other languages.