Backlund started playing trumpet at the age of seven in a youth brass band led by his father, at the Church of Paavali in Helsinki.
At 14 years of age, he founded his first big band, which also included Paroni Paakkunainen, Teppo Hauta-aho, Eero Ojanen, Pekka Pöyry, and Juhani Aaltonen.
Later, Backlund had to take a day job as an assistant accountant, but was able to participate in the Jyväskylä Arts Festival in 1966 and 1967, where George Russell was teaching.
In the beginning of the 1970s, Backlund started to arrange Toivo Kärki's songs.
Kaj Backlund's sons Jari, Jukka, and Tapio are all musicians.