Which studio was the primary developer of Assassin's Creed II?

Ubisoft Montreal was the primary developer of Assassin's Creed II.

The Montreal studio led development of the 2009 sequel, which expanded the original game's stealth and exploration systems while moving the historical story to Renaissance Italy. Ubisoft published the game, but primary development responsibility belonged to Ubisoft Montreal, with support from other Ubisoft studios.

Assassin's Creed II follows Ezio Auditore across locations including Florence, Venice, and Monteriggioni. It introduced a broader range of weapons, economic upgrades, activities, and character interactions than the first game. The title became one of the most influential entries in the series and established Ezio as a major recurring protagonist.

Ubisoft Quebec later led development of Assassin's Creed Odyssey, while Ubisoft Sofia worked on projects including Assassin's Creed Rogue and Liberation-related development. Ubisoft Singapore has contributed to several franchise projects, but those studios were not the primary developer of Assassin's Creed II.