Born in Helsinki, Petri Sakari studied the violin, piano and oboe from an early age. He enrolled at the Tampere Conservatory, turned to conducting in 1974 and soon after went on to study with Jorma Panula at the Sibelius Academy in Helsinki, receiving diplomas in conducting and violin in 1981. After attending master-classes with Murry Sidlin at Aspen, Franco Ferrara in Siena and Rafael Kubelík in Lucerne, he soon conducted the Tampere Conservatory Symphony Orchestra and opera productions at the Sibelius Academy. Since 1983 he has had regular engagements with Finnish orchestras such as the Vaasa City Orchestra, Finnish Radio Symphony Orchestra and Lahti Symphony Orchestra, among others.

Following successful appearances outside Finland, Petri Sakari joined the Iceland Symphony Orchestra as chief conductor in 1988, continuing as principal guest conductor from 1993 to 1996 and, again, as chief conductor from 1996 to 1998, making a number of acclaimed recordings. Chief conductor of the Lohja Symphony Orchestra from 1993 to 1999, principal guest conductor of the Swedish Chamber Orchestra from 1995 to 1997, and music director and chief conductor of the Gävle Symphony Orchestra from 2000 to 2004, he assumes the post of chief conductor of the Turku Philharmonic Orchestra in 2007. He has conducted opera and ballet performances at the chief opera houses of Finland, Sweden and Iceland, and also guest conducted orchestras throughout Europe and in São Paolo, Singapore and Mexico City.