Marko Valtonen began studying the accordion under the guidance of Keijo Louna in Lieto in 1979. He continued his studies in the youth education program of the Sibelius Academy in 1982, where his teachers were Heidi Velamo and Matti Rantanen. Valtonen studied in the soloist department of the Sibelius Academy, majoring in accordion with harpsichord and piano as minors, until 1998, when he graduated with a Master of Music degree. His teachers included Prof. Matti Rantanen (accordion), Kati Hämäläinen (harpsichord), and Jarmo Eerikäinen (piano). In 2003, Valtonen furthered his accordion studies at the State University of Music in Trossingen, Germany, under the direction of Prof. Hugo Noth. In 2023, he began collaborating with body therapist and mental coach Saara Sahrman. Since then, Sahrman has served as Valtonen's personal coach.

Since 1999, Valtonen has served as an accordion teacher at the Turku Region Music Institute. Following the merger of the Turku Region Music Institute and the Turku Conservatory, he now continues his teaching work as a lecturer in accordion at the Turku Conservatory.

Valtonen’s repertoire ranges from works of the 17th century to contemporary music. Baroque music, and especially the music of Johann Sebastian Bach, has always held a special place in his repertoire. French musette and chanson traditions, as well as Finnish and Argentine tango, have also played a significant role in his performances. In addition, he has performed in several theater productions, such as Evita, Les Misérables, West Side Story, Amélie and The Last Ship He has performed widely both as a soloist and in various chamber music ensembles, not only in Finland but also in the Nordic countries and Central Europe.

Valtonen’s 2026 concert program features Italian and Spanish influences from the Baroque period. The composers represented include Domenico Scarlatti, Johann Sebastian Bach, and Remo Giazotto.