Mongo Aaltonen started studying percussion at the age of 16-17 with the help of Upi Sorvali. Then he continued to Porin Musiikkiopisto and started playing in the Pori Big Band. His academic career began in 1981 with classical percussion studies at the Sibelius Academy, but little by little his interest turned towards Afro-Cuban and Latin American music.
He has played in several jazz and pop bands, such as Olympia-orkesteri, Pori Big Band, UMO (2) and Jukka Linkola Octet. He has also played in the backing bands of Jari Sillanpää, Pepe Ahlqvist and Heikki Silvennoinen. Aaltonen can be also frequently seen on the stage with theater and symphony orchestras. His music has also been heard in several films. In addition, he is a studio musician.
Aaltonen often works with the drummer Anssi Nykänen.