Hannula was drafted in the 2002 NHL Entry Draft by Minnesota Wild with their 9th choice, 269th overall selection. During his career, he has played for three different hockey teams in the Stockholm area: AIK Hockey, Djurgårdens IF and Hammarby IF. He also tried playing in the United States for the Houston Aeros in the American Hockey League during the season 2003–04, totalling 27 points in 67 regular season games.