Originally, it was a quartet whose members included flautist Claire Guimond, violinist Chantal Rémillard, harpsichordist Hank Knox, and viola da gamba player Betsy MacMillan.

Since the mid-1990s, the original quartet has expanded with the aim of developing into a baroque orchestra, and thus began to explore the repertoire from the 2nd half of the 18th century, most notably the music of Haydn and Mozart.

Some of the collaborators Arion has shared the stage with over the years are sopranos Suzie LeBlanc and Karina Gauvin, recorder player Vincent Lauzer, violinists Stefano Montanari, Enrico Onofri, and Monica Huggett, cellist Jaap ter Linden, harpsichordists Christophe Rousset, Garry Cooper, and Alexander Weimann, flautist Barthold Kuijken, and clarinettist Lorenzo Coppola.

Arion Baroque Orchestra has toured Québec, Canada, the United States, Mexico, Brazil, Japan,[3] and Europe.

The discography of Arion Baroque Orchestra comprises around thirty titles[10] on four labels: early-music.com,[11] ATMA Classique,[12] Analekta,[13] and the Canadian Broadcasting Corporation.