The Australian arrived at Gloucester in September but was due to return down under to play for the Melbourne Rebels in next year's Super Rugby competition.
However, the 29-year-old has enjoyed himself so much, he has now opted to extend his stay in the Aviva Premiership.
"I've loved every minute of my time here. It's a great bunch of lads and they've made me incredibly welcome from day one," Hanson told Gloucester Rugby's official website.
"I was obviously supposed to be heading back down under at the end of the year, but Gloucester told me that they'd like me to stay on and I'm grateful to the Rebels for handling it all so professionally.
"Playing in front of the Gloucester fans has been amazing, they're so passionate in their support of the team and they've been terrific to me.
"I have great belief in the direction that [head coach] Johan [Ackerman] is taking the squad and I can't wait for the rest of the season now."