He continued to play in Victoriaville until his final year of major junior in 2010, posting 2.63 GAA and .916 save percentage, his best career QMJHL numbers.

Poulin began the 2010–11 season playing with the Islanders' American Hockey League (AHL) affiliate, the Bridgeport Sound Tigers, but on January 4, 2011, was recalled to the NHL due to an injury to Rick DiPietro.

Entering the Stanley Cup playoffs for the first time since 2007 as the eighth seed in the Eastern Conference against the top-seeded Pittsburgh Penguins, Poulin replaced Nabokov in Game 1.

In late December 2017, he helped Team Canada win the prestigious Spengler Cup in Davos, coming up with an impressive performance in the championship game.

Having returned to North America prior to the 2019–20 season, on December 26, 2019, the Grand Rapids Griffins signed Poulin to a professional tryout (PTO).

As a free agent from the Kings, Poulin opted to return to Europe by agreeing to an optional two-year contract with Swedish second-tier club, IF Björklöven of the HockeyAllsvenskan, on July 7, 2020.

On June 29, 2021, Poulin opted to end his tenure in Sweden, agreeing to a one-year contract with the Montreal Canadiens, AHL affiliate and hometown club the Laval Rocket.