Heini Kärkkäinen studied piano at the Sibelius-Academy under Liisa Pohjolaand continued her studies with Ralf Gothóni and Jacques Rouvier among others. She won the Ilmari Hannikainen Piano Competition in 1984 and two years later she came second in the Maj Lind Piano Competition.
She has performed as soloist with orchestras e.g. Finnish Radio Symphony Orchestra, Helsinki Philharmonic Orchestra, Orquesta Ciudad de Granada and Orchestra della Svizzera Italiano. She has also played chamber music extensively in Europe and in the United States. She has also visited numerous festivals.
Kärkkäinen has given first performances of many contemporary Finnish works by e.g. Jouni Kaipainen, Mikko Heiniö, Magnus Lindberg, Aulis Sallinen ja Olli Koskelin, and made several prizewinning recordings. Record with Jan-Erik Gustafsson (Ondine) was awarded as the record of the year 1994 by Finnish broadcasting company.
Alongside with her soloist career Heini Kärkkäinen has since 2010 operated as the Principal Lecturer in the Tampere University of Applied Sciences.