The Legend of Zelda Tri Force Heroes is Canon
What’s more, according to Nintendo themselves, the game stars the same Link from A Link Between Worlds and takes place shortly after said game. Here’s the post where they confirm this:
— Nintendo of America (@NintendoAmerica) October 22, 2015
So what’s there to say? Well to be honest, quite a bit, given how many different answers we’ve been given in regards to this game’s timeline placement and canon status. At least one developer said it could go anywhere, and a Nintendo marketing person said it wasn’t canon at all. So apparently the people at the company didn’t have any idea about the game and its status until quite recently.
Either way, the game is now confirmed canon, and is part of the Zelda timeline.