Thornton, who has also been upgraded from Rookie to a full contract at Cricket NSW, will join the squad full time this season where he will look to add to the game he played last season in magenta.
He will join a bowling line-up that includes last year’s stand out Ben Dwarshuis, Test bowler Jackson Bird, Sixers Player of the Tournament Sean Abbott and Captain Moises Henriques, as well as spinners Steve O’Keefe, Johan Botha and when available, Nathan Lyon.
His inclusion comes off the back on playing for the CA XI in the recent JLT Cup where he played three games in the series.
Thornton said his goal was to learn as much as he could from the experience within the squad.
“I’d love to learn as much as I can from the senior players,” Thornton said.
“Obviously any game time is a bonus because it’s so much fun and so exciting being out there in front of our fans, but as much as I can learn from the older boys that’s what I’m going to do.
“It’s great to have the majority of the squad we had last year, we built something really special last year and that’s down to our coach Greg Shipperd and Moises as well. It felt like a family last year and hopefully we can bring that culture in again this year, and hopefully win that title.”
Head Coach Greg Shipperd said the BBL was a great breeding ground for young talent.
“We are very pleased to have exciting young paceman Henry Thornton rejoining our list,” he said.
“Henry continues his journey with the Sixers and offers us some genuine pace and will complement our new ball options in Jackson Bird, Ben Dwarshius and Mitchell Starc.
“He made his debut at the Gabba and played an important role in a crucial game for us and we look forward to him playing a significant role within the franchise as a long term player.
“This competition is becoming a wonderful platform for new talent Henry fits the bill as one of New South Wales' next generation of pacemen."
The Sixers start their BBL|07 campaign on Tuesday 19 December against the Sydney Thunder at Spotless Stadium, followed by their first home game of the summer at the SCG against the Perth Scorchers on 23 December.
The BBL|07 squad is: Moises Henriques ©, Sean Abbott, Jackson Bird, Johan Botha, Ben Dwarshuis, Daniel Hughes, Nathan Lyon, Nic Maddinson, Peter Nevill, Stephen O’Keefe, Jordan Silk, Mitchell Starc, Henry Thornton