Share of the Brienz-Rothornbahn-AG, 1892

The railway was opened on 17 June 1892, after a two years construction period. The two designers, engineer Alexander Lindner and contractor Theo Bertschinger were supported by the mountain railway pioneer Roman Abt, who had responsibility for equipping the line with his newly developed Abt double lamella rack system.

The line connected at Brienz with the Brünig railway line, which had been opened in 1888 from Brienz eastwards towards Lucerne. However, the Brünig railway was not extended westward to Interlaken until 1916, so many early travelers to the Rothorn had to arrive by boat service on Lake Brienz.[1]

The line was quickly in financial difficulties. The line was designed to carry 25,000 passengers per year, but only managed 5,000 passengers in the first year. Tourist traffic was further affected by the opening of Schynige Platte Railway in 1895 and the Jungfraubahn in 1898. Train service was suspended on 1 August 1914 as a result of the First World War, but did not resume when the war ended.

Essential maintenance was carried out and a small amount of timber traffic was carried from Planalp in 1918. Carriages were hired to the Schynige Platte Railway in 1924 and 1925, providing funds for the maintenance work. The line was finally re-opened on 13 June 1931, the first train to reach the summit in 17 years having run four days earlier. The railway was in good condition because of the continued maintenance.

Unlike other Swiss mountain lines, the BRB was not electrified and this made the railway a special attraction as from 1953 to 1990 it was the only steam-operated line in Switzerland. Although other Swiss mountain railways offer special "steam" trips, this is the only line to offer a full steam service, the Diesel locomotive only being used for additional trains and for light traffic periods.