The 28-year-old joins the French side from Danish side FC Midtjylland.
“It’s a big step in my career,” Poulsen told Monaco’s official website.
“I am joining a big club, even though Monaco are in Ligue 2 at the moment.
“A few years ago they were one of the best clubs in Europe and I know their ambition is to get back to that level.
“It will take time, but it is a big challenge.”
