Maggs has spent the last few seasons with Ulster, having initially left Bristol for Bath in 1998.
Bristol head coach Richard Hill said: "I have obviously looked in the past to try to bring players to Bristol who have a link with the club, and that link isn't any stronger than it is with Kevin.
"He is a Bristol lad through and through, and he probably wouldn't have left the club if it had not been for relegation and his need to further his international career."
Linklater, meanwhile, will link up with fellow Bristol newcomers and ex-Waikato colleagues David Hill and Sean Hohneck, who have already featured in Bristol colours this season.
The 27-year-old has agreed terms until the end of season 2008-09, and he will not count as a foreign player due to his wife being English.
Richard Hill added: "We are looking, potentially, at a very exciting and very busy end to the season, what with going well in the league and also trying to get as far as we can in the European Challenge Cup.
"So Scott, with his track record in Super 14s, will further strengthen the squad for the run-in. We will need that strength in depth to give us the best possible chance of a really good end to the season."