The three-time British & Irish Lion has arrived back in Wales following three years in France with Toulon and is set to make his debut on September 2 against the Southern Kings.
Full-back Halfpenny was also tracked by former club Cardiff but eventually opted for the Scarlets, signing a three-year dual contract in Llanelli, with the WRU expected to pay 60 per cent of his salary.
Former fly-half Jones played with the 28-year-old for Wales and says he and everyone else at Parc y Scarlets have been impressed by the new boy's attitude, conceding the region are extremely fortunate to have him around.
"Everyone knows his abilities and he is a wonderful player and a great person," said Jones. "We're very lucky Leigh decided to join us.
"All the players and coaches in the squad are looking forward to working with him. He's already joined the squad and has brought a positive attitude."