The Sortavala Lyceum began its activities as the town lyceum in autumn 1893 after a long wait. The lyceum was established to consist of five grades, and its entrance criteria and courses equalled those in state schools. The objective was to give the town a full state lyceum consisting of five grades, which was realised in 1898 when the lyceum became the official State Lyceum of Sortavala. A separate building owned by the lyceum was set as a goal soon after the establishment of the school, but even as a state school the first years went by in rented facilities. First, the lyceum operated in the house of Principal C.W. Alopaeus, then in the house of Lector E. Mäkinen. After a fire in the latter, it moved back to temporary premises at the seminar and later to the building of the Evangelical Association. The resources of the town of Sortavala were not sufficient for the construction of a lyceum building, but it was completed in 1901 constructed by the Finnish government. The two-floor stone building, built on a plot in Kisamäki hill, was designed by Jac Ahrenberg (1847–1917), who, at the time, held a the position of the first architect of the Board of Public Buildings.
The first matriculation examinations were held in spring 1901. As the academic year 1914–1915 started, the school was given the name the Sortavala Lyceum. Soon the number of students rose to 200 boys. In the academic year 1929–1930, the lyceum had a total of 340 students, all boys. Approximately half of the students at the lyceum were from Sortavala. From mid-1920s onwards, the proportion of students hailing from the rural municipality was increased through the growth of suburbia, and at the start of Winter War almost 90 per cent of the students were either from the town or the rural municipality of Sortavala.