Wales international Halfpenny spent three years with Toulon between 2014 and 2017, but he was not offered a new contract with the French club during the summer and he subsequently returned to his homeland with Scarlets.
However, the 28-year-old will now return to the Stade Mayol this weekend, as both clubs get their European campaigns underway, and he admits he is looking forward to seeing some familiar faces upon his return.
"I'm looking forward to going back out to Toulon with the Scarlets and after the game catching up with some of the guys that I played with during my time there," Halfpenny told Sky Sports. "But during the game it'll be a huge battle, that's the exciting part."
It is the second year in a row that Toulon and Scarlets have met in the Champions Cup, as they also clashed during last season's group stage, with both club's winning their respective home matches.
Indeed Halfpenny successfully kicked four conversions and a penalty to help Toulon to victory in France last December, but he also missed a crucial kick as Scarlets won out 22-21 during the return match in Wales.