Saints have snapped up Travis Burns from Hull KR on a three-year deal from 2015, paying the Humberside club a £60,000 transfer fee.
The Australian will link up with his new teammates in the off-season.
Chairman Eamonn McManus said: “Travis is a key signing for us for and will bring both quality and depth to our half back options and combinations.
“He is a proven and experienced stand off and will also bring directness and toughness as well as a strong kicking game.”
Predominately a stand-off, Travis, 30, began his professional rugby league career at Manly.
He was the Sea Eagles’ rookie of the year in 2006 and then joined North Queensland in 2008.
Burns played for the Cowboys for two seasons, making more than 30 appearances and scoring seven tries, before he moved to Penrith Panthers prior to the 2010 season.
There he linked up with Luke Walsh and went on to appear 55 times for the Panthers amassing more than 100 points in the process.
That attracted the attention of Hull KR in Super League in 2013 and the half back wasted no time in showing the competition why he is one of the best in the business.
He has gone on to make more than 40 appearances for the Robins, scoring close to 200 points.
“Whilst I’m sad to leave Hull KR - they have been great to me and my family - I am really excited to be joining Saints,” Burns said. “It will be great linking with my friend and former teammate Luke Walsh and what is an exciting and strong squad.
“Saints have a strong team that is looking to win silverware over the next few years and I am excited and looking forward to being part of that.”
Nathan Brown, Saints’ head coach, added: “Travis is a great competitor and will bring that to the club. He will also add good depth to our halves and we’re looking forward to having him on board.”