Head coach of the time Stuart Raper said: "Harrison has impressed me this season in the Under 21s and he is another quality young player to come through the ranks joining the likes of Luke Robinson, Gareth Hock and Kevin Brown."

Rugby Executive Dean Bell commented, "Harrison possess all the right qualities to become a regular first grade player, he has come through our scholarship system and has been outstanding in our Under 21 side this season.

In 2005, Hansen became a more established first team regular in the second row, partly due to the departure of Andy Farrell, and injuries to Sean O'Loughlin and Gareth Hock.

[7] Hansen's 2011's Super League XVI started with a try against St Helens during the season-opening Magic Weekend event, which was followed up with another try against Bradford Bulls the week after.

[10][11][12] Hansen played as a second-row forward in the 2011 Challenge Cup Final 28–18 victory over the Leeds Rhinos at Wembley Stadium.

[26] On 10 October 2021, Hansen played for Toulouse in their victory over Featherstone in the Million Pound Game which saw the club promoted to the Super League for the first time in their history.

[28] Hansen played 20 games for the club in their 2022 Super League campaign as they finished bottom of the table and were relegated back to the RFL Championship.

[29] On 15 October 2023, Hansen played in Toulouse Olympique's upset loss in the Million Pound Game against the London Broncos.