Sanna Vaarni began her studies at the Espoo Music Institute with professor Katarina Nummi-Kuisma. She studied in Sibelius Academy with professor Eero Heinonen, chamber music  with Ralf Gothóni and lied music with Gustav Djupsjöbacka. Supported by a grant by Wihuri Foundation, she spent 1997-1999 in Paris studying with professor Konstantin Bogino and lied music with Armande Olivier.

Sanna Vaarni has been a prize winner in many national piano competitions (Ilmari Hannikainen Piano Competition, Helmi Vesa Piano Competition, Fazer Piano Competition). She performs regularly as a soloist, chamber musician and lied pianist. She has given concerts in Estonia, France, Germany, Latvia and in Saudi Arabia. She has been recording for the Finnish Broadcasting Company (YLE).

Currently Sanna Vaarni works as a professor of piano and is also the Head of Piano Department at the Espoo Music Institute. During recent years she has been giving master classes in music institutes and conservatorys in Finland and she has been lecturing for teachers in the department of continuing education in Sibelius Academy. Her students have been among prize winners in both national and international piano competitions.