The Book Night events were initiated by Sanje publisher boss Rok Zavrtanik, who got the idea from Croatia.
The events will include 23 organisers and some 400 event hosts around Slovenia, Zavrtanik told the press as he announced the event.
The most of the events – ranging from book readings, exhibitions, performances and film screenings – will be held in Ljubljana and its surroundings.
Event hosts around the country include libraries, schools, associations, publishers and book stores.
UNESCO's World Book Day was first observed in 1995. It is usually observed on birth or death anniversaries of several important writers such as Miguel de Cervantes, Vladimir Nabokov and William Shakespeare.