During the 1960s, Kalniņš led the Liepāja rock band 2xBBM, which was extremely loved because of its heartfelt songs and hippy-like lifestyle. Kalniņš became the symbol of the spirituality, rebellion and worldview of the generation, and it was emphasized by the fact the band was forced to stop playing because of the pressure from official institutions. However, this doesn’t stop the music of Kalniņš from being heard - it is played by the incredibly popular band Menuets (Latvian for ‘minuet’), which plays songs almost exclusively by Kalniņš.
During the 1970s, Kalniņš returned to writing symphonic music. In 1984, he wrote the rock oratorio Kā jūra, kā zeme, kā debess/ “Like the sea, like the earth, like the sky” together with Juris Kulakovs and Juris Sējāns. The oratorio was the first thing played by the band Pērkons (‘Thunder’) for the general public. With it Kalniņš returned to rock and roll once more. He wrote many new songs for Pērkons, and these same songs led him to start his own band, Turaidas Roze (‘The Rose Of Turaida’). However, the band never gained the recognition and adoration that Menuets and Pērkons did.
Lately Imants Kalniņš has been working together with the well-known Latvian musician Ainārs Mielavs, and their collaboration has resulted in some of the most excellent albums containing primarily music by Kalniņš, such as Par lietām, kuras tā ar nekad nepāriet/ “About things that never truly go away” (1997), Es redzēju sapnī/ “I Saw in a Dream” (1998) and I Love You (1999; despite the title, the lyrics are mostly in Latvian in this album).
He is also a politician, member of the 8-th Saeima for For Fatherland and Freedom.