Mari Sainio (b. 1989) is a Finnish composer who works in different types of classical music and movie projects worldwide. Sainio has composed many choral music, operas, and orchestral song cycles.

Sainio has been busy as a composer since 2010 composing music for different types of classical ensembles as well as film, theatre, and opera stages. Commissions include projects with Finnish broadcasting company YLE, Icelandic production company NyArk Media, SonyATV, TampereRaw, Nordic Music Days, the Baltic Sea Philharmonic, and Imogen Heap. Sainio’s works have been performed in prestigious venues such as The National Gallery (London), Music House (Helsinki), and the Victoria and Albert Museum (London) and she has also won numerous prizes for her film scores.

In the summer of 2017 her debut EP, Tales, was released to critical and popular acclaim on the Finnish Ranka Kustannus label followed by her debut album Minus 25. Her second album Archipelago Stories and recording of her opera The Raven were released in 2022. Her third album Natt will be released in 2025.

Sainio has graduated from the Royal College of Music and Sibelius Academy.