He moves to Gloucester having enjoyed a successful spell with the Tasman Makos in New Zealand, who recently secured silverware by winning the ITM Championship.
The Gloucester squad has undergone some changes in recent months following the retirement of Olly Morgan and departure of Tim Molenaar to Harlequins, and Puafisi's arrival will add strength to the front row.
An international team mate of Sione Kalamafoni and Lua Lokotui, he will start with Gloucester shortly, subject to visa approval, ready to play his part in the second half of Gloucester's season.
Director of Rugby Nigel Davies told the club website that he's delighted to have another front row option at his disposal.
"We identified Sila as a possible addition to the squad and I'm very pleased that we have been able to bring him in.
"It's taken quite a lot of work, the work behind the scenes in these cases can often be quite lengthy. But he's been in fine form in the ITM Cup and for Tonga, and I'm confident that we have added a quality player to the squad.
"Having Lua (Lokotui) and Sione (Kalamafoni) here already has been a big help. Sila has been able to find out more about Gloucester from them and, in turn, they've confirmed that we've got the right man.
"His arrival will allow our front row options to be deeper and also create competition in that position, which can only be a good thing going forward."