Mirja Mäkelä (b. 1968) started her piano lessons at the Espoo Music School when she was 6-years-old and sang at home after the albums of Ella Fitzgerald already at a very young age. Her big sister, who sang in the a cappella ensemble Opus 5, was an important example for Mäkelä and she says that in her teens she was more interested in jazz than pop music. Her vocal skills developped in the music high school of Tapiola but piano stayed as her main instrument till the department of music education of Sibelius Academy where Mäkelä was accepted in 1998.

Singing however started to attract Mäkelä more and more and the final push to the career of a vocalist were the jazz jam sessions of the restaurant Orfeus that Mäkelä participated actively in spring 1991. Pianist Kirmo Lintinen, who also played in those jam sessions, encouraged her to apply to the jazz department of Sibelius Academy and even though she didn't get in on her first try, Jukkis Uotila noticed her skills and on her next attempt in 1992 Mäkelä was accepted.

Mäkelä performed in the UMO Jazz Orchestra's Young Soloist concert in 1993 and won the next year the Lady Summertime jazzvocal competition. Already on her first year at Sibelius Academy she founded her own band, consisting of pianist Kirmo Lintinen, bassist Ape Anttila, drummer Markku Ounaskari and the young promising saxophonist Manuel Dunkel. Mirja Mäkelä Band did the Finnish Jazz Federation's tour in 1994 and 1995, performed on several Finnish jazzfestivals, did a tour in Germany and released an album in 1999.

Mäkelä has built her career as a strong vocalist also with her own quartet and a trio consisting of Swedish jazzmusicians. She performed as the soloist of the trio first time in 2000 in Jazz aux Oydayas Festival in Marocco that had European jazzartists and groups as a theme of the festival. Mäkelä-Berger-Knutsson-Spering did a few tours in Finland and Sweden and released an album Arco Íris (Texicalli/ Impala) in 2003. The album, that songs were mainly composed to the lyrics of Mäkelä and other Finnish lyricists, got an extremely warm welcome both in Finland and in Sweden. The meaning of the group of Mäkelä and the Swedish musicians were noticed as an important brige between the two cultures and in spring 2007 Mäkelä was awarded with the cultural Proze of the Finnish-Swedish Culture Foundation.

In 2001-2009 Mäkelä sang in JimJamMurMur-quartet with Johanna Iivanainen, Mia Simanainen and Jenny Robson. JimJamMurMur won the group competition of the Tampere Vocal Music Festival in 2003 and did a Finnish Jazz Federation's tour in 2002. Mäkelä's current ensemble is a chamber jazz trio with guitarist Tuomo Dahlblon and bassist Juho Kivivuori. The trio's former members include Teemu Viinikainen and bassist Lasse Lindgren. Mirja Mäkelä Trio has released two albums, Runoisa (2008) and My Hidden Joys (2015). A new album will be released in 2022. Mäkelä has also visited UMO as a composer and soloist in 2006 and once in a while many other big bands as well, such as Espoo Big Band and Estonian Dream Big Band.

Mäkelä started to teach singing already before she even graduated from the Sibelius Academy. In 2006-2007 she both taught and worked as the vice head master for Ebeli, the pop/jazz department of Espoo Music School EMO and in 2007-2009 she worked as the head master for Ebeli. In 2010 Ebeli merged with EMO and Mäkelä was appointed as the head of the department. Since August 2021, Mäkelä has been on leave from Ebeli.