Kadri Toomoja started playing the piano at the age of 4 under the guidance of teacher Reet Jürgens. He graduated from Tallinn Music High School (2013, teachers Anu Nahkur and Toivo Nahkur) and the Estonian Academy of Music and Theater with a bachelor's degree in piano (2017 cum laude, Prof. Toivo Nahkur), where he continued his master's studies in the organ major under the supervision of Professor Andres Uibo. From the fall of 2020, Toomoja will study at the Sibelius Academy in Finland under the supervision of Professor Olli Porthan. He has participated in the master courses of Ton Koopman, Matthias Schneider and Krzysztof Urbaniak. In 2020, Kadri Toomoja received a scholarship named after Tõnu Kaljuste. As a student and freelance musician, Toomoja has played with several prestigious ensembles, among them the Estonian National Symphony Orchestra, Tallinn Chamber Orchestra, Estonian Philharmonic Chamber Choir, Estonian National Male Choir, Ellerhein Girls' Choir, Voces Tallinn and Collegium Musicale; with conductors Tõnu Kaljuste, Paavo Järvi, James MacMillan, Risto Joosti, Mikk Üleoja, Anu Tali, Toomas Kapten, Ingrid Kõrvitsa, Endrik Üksvärava, Kaspar Mändi etc. Toomoja has given solo concerts both in Estonia and Finland, performed as a soloist before the Tallinn Chamber Orchestra and took part in several festivals such as Helsinki Organ Festival (Finland, 2020), Arvo Pärt Days (Belgium, 2019), Nargenfestival, Tallinn International Organ Festival, Mustjala Festival, Europa Cantat etc.
Toomoja is also a valued concert master among both singers and instrumentalists. Since 2017, Toomoja has been working with baritone Alvar Tiisler. In addition to the long-term cooperation with the girls' choir Ellerhein, he has also worked as a concertmaster at instrumentalist competitions (Noor Muusik, international Artur Kapp cellist competition) and worked as a concertmaster for conductors at EMTA.