Rajkumar was also a well-known singer. He sang many devotional songs. He won the National Award for the song “Naadamaya” from the movie Jeevana Chaitra. He had trained in classical music while in Gubbi Veranna’s drama troupe. At that time it was required for everyone to at least have a working knowledge of classical music. He performed a song in the movie Mahishasura Mardini with G. K. Venkatesh as the music director. However, he did not become a full-fledged singer until his hugely popular song “Yare Koogadali” from the movie Sampathige Sawal. Prior to his singing in Sampathige Sawal, Rajkumar’s songs were sung by P. B. Srinivas. He used to call Srinivas ‘Shaareera’ while he referred to himself as ‘Shareera’. After “Yare Koogadali”, he sang in most of his movies and in many private albums, which were mainly devotional albums. His song renditions ranged from pure classical to disco and fast numbers to pathos. Although his singing was greatly appreciated, his fans of the days of black-and-white movies in 1960s and 1970s, swear by the fact that his true identity was P. B. Srinivas, who did the playback singing for most of Rajkumar’s movies, until Rajkumar himself started to sing. P. B. Srinivas continued singing for him in many of the movies in which Rajkumar starred in double/triple roles.
In his final years, Rajkumar lent his voice to a few other actors and sang many background solos. One such song, which holds a unique distinction, was for the 1993 movie Muddina Maava, wherein he provided playback to the legendary singer S. P. Balasubramaniyam, who acted in the movie. This was a rare occasion where an actor sang for a singer, probably unmatched in the world of cinema. He sang many devotional songs on Hanuman and Sri Raghavendra Swamiji. One of his most famous songs was “Huttidare kannada nadalli hutta beku”.
Rajkumar’s voice had a smoothness and depth comparable to that of playback singer P. B. Sreenivas. His voice was also capable of great vivacity, noticeable in songs like “muttu koduve kandane nanna muddu raaja”, “Sigivem Kshanadali”, “Thai Thai Bangari”, “Naa Ninna Mareyalare”, “Le le Appana Magale” and “Aradhisuve”. His childhood theatrical background helped him in acting as well as singing. He was adept at rendering his voice to different genres: romantic, sentimental, devotional and semi-classical. His songs about Kannada language and culture, such as “Jenina holeyo”, “Maanavanagi huttidmele” and “Huttidare”, are immensely popular. He even sang a complete English song in one of his Bond films. “Naadamaya”, a classical song in Raga Thodi, which won him the national award for best playback singing, demonstrates his versatility as a singer with its complex graces as it progresses with other ragas. He switches between ragas with ease and sings Swara patterns like a professional.
Kalidasa’s shlokas (songs) like Sadaa Kannali, Kanneera Dhaare, Gelathi Baradu and Yaava Kaviyu, have also become very popular. In addition to his film work, he rendered his voice for many devotional songs.