Robert Kajanus was among the handful of Finnish conductors to achieve a worldwide reputation in the early 20th century. In doing so, he also preserved authoritative performances of the work of his countryman Jean Sibelius for posterity.

Kajanus studied at the Helsinki Conservatory, and later at Leipzig with Hans Richter. He worked in Dresden in the years immediately after his graduation, and returned to Helsinki in 1882. He founded the Helsinki Philharmonic Society, the first permanent orchestra in Finland, and brought the orchestra to a very high performance standard very quickly, so that they were able to give quite credible performances of the standard late classical/mid-romantic repertory. Kajanus led the Helsinki Philharmonic for 50 years, and among the milestones of that history was the first performance in Finland of Beethoven's Symphony No. 9, in 1888.

Kajanus was the most prominent Finnish composer before Jean Sibelius, and his music, which drew on the folk legends of the Finnish people, proved a major influence upon the younger Finn. Sibelius's epic masterpiece Kullervo was written in the wake of Kajanus' symphonic poem Aino. Additionally, as a conductor, Kajanus was responsible for commissioning one of Sibelius' most popular and enduring works, En Saga, in the wake of Kullervo. When Kajanus took the Helsinki Orchestra on a tour of Europe in 1900, both he and Sibelius served as conductors, in what proved to be the first performances of Sibelius's music outside of Finland. This ensured the spread of the young composer's reputation far beyond the borders of his homeland, the first Finnish composer to receive such attention.

Kajanus was appointed director of music at Helsinki University in 1897 and remained in the post for the next 29 years, a period in which he had a major impact on music education in his native country. He was also the founder of the Nordic Music Festival in 1919.

The relationship between Kajanus and Sibelius was such that his interpretations of the composer's music are usually regarded as being extraordinarily close to Sibelius's own wishes. Although there were younger conductors who embraced Sibelius's music around this time, including Sir Thomas Beecham, Kajanus remained the definitive interpreter of these works. In 1930, the Finnish government and Britain's EMI-Columbia label, perceiving a potentially wide audience for the composer's work, contrived to secure recordings of Sibelius's first two symphonies, and Kajanus was selected to record both at the insistence of the composer. In 1932, Kajanus recorded the Symphonies Nos. 3 and 5, along with several of the orchestral suites and tone poems. Apart from being the most massive recording project ever attempted around the work of a living composer, these recordings were considered definitive for many years, and are still regarded as necessary listening for serious fans of Sibelius. Only his death in July of 1933, at the age of 76, prevented Kajanus from recording the composer's complete extant works. ~ Bruce Eder, Rovi