Petri, who began playing the recorder at the age of three, is noted for her virtuosity and versatility across a wide range of styles, from the baroque repertoire of the height of the instrument's popularity to contemporary works written particularly for her. She has premiered dozens of works, by composers Malcolm Arnold, Gordon Jacob and Richard Harvey, as well as Daniel Börtz, Erik Haumann, Hans Kunstovny, Erling Bjerno, Thomas Koppel, Ove Benzen, Vagn Holmboe, Piers Hellawell, Gary Kulesha, Asger Lund Christiansen, Egil Harder, Michael Berkeley, Butch Lacy, Miklos Maros, Ezra Laderman, Jens Bjerre, Henning Christiansen, Niels Viggo Bentzon, Axel Borup Jørgensen, and Gunnar Berg.
She frequently collaborates with her former husband (they divorced in 2010), guitarist and lutenist Lars Hannibal, with whom she has made several recordings. Petri has taken a particular interest in the combination of recorder and guitar, collaborating with guitarists including Göran Söllscher, Kazuhito Yamashita and Manuel Barrueco. One notable collaboration of hers was two albums of sonatas by J. S. Bach and G. F. Handel, with Keith Jarrett on harpsichord; she has also recorded with the London Philharmonic Orchestra, the English Chamber Orchestra, and Pinchas Zukerman, among many others.
Petri studied with Ferdinand Conrad at the Staatliche Hochschule für Musik und Theater in Hannover. Her mother is Hanna Petri, who studied at the Royal Danish Academy of Music, and her brother, David Petri, won the Danish "Young Musician of the Year Award" in 1978. He is a cellist. Both have recorded with Michala as The Petri Trio. In 1979 she began an exclusive recording contract with Philips Records that lasted until 1987; she is currently recording on the RCA Red Seal label.
- Los Angeles Street Concerto - Petri plays Koppel
- Souvenir with Lars Hannibal
- Moonchild's Dream with the English Chamber Orchestra
- Scandinavian Moods with the London Philharmonic Orchestra
- The Ultimate Recorder Collection with Those above, The Westminster Abbey Choir, Keith Jarrett, and Moscow Virtuoso (on separate tracks)
- Grieg Holberg Suite, Melody & Dances with the English Chamber Orchestra
- Greensleeves with Hanna and David Petri
- Tagea Brandt Rejselegat (1981)
- Knight - Order of the Dannebrog 1995
- Deutscher Schallplattenpreis 1997
- H. C. Lumbye Prize 1998
- Wilhelm Hansen Music Prize 1998
- Léonie Sonning Music Prize 2000, she was the third Dane to win this prize, after Mogens Wöldike (1976) and Per Nørgård (1996)
- Nockin, Maria (4 February 2012). "Michala Petri Plays Very Old and Very New Music". Fanfare. Archived from the original on May 29, 2012. Retrieved 21 March 2016.
- .Bruce Duffie Interview With Petri, Chicago WNIB, Classical 97
- Los Angeles Street Concerto - Petri plays Koppel Dacapo Records Denmark, released April 2006
- Petri Winning Wilhelm Hansen Music Prize 1998 Edition Wilhelm Hansen, a leading-Danish music publisher.
- Petri Winning Léonie Sonning Music Prize 2000 Léonie Sonning Music Prize Laureates
- Program notes from various CDs, Including Philips CD #420 897-2 "Greensleeves"