Irish quartet Garbhan Coughlan, Conor O'Keeffe, Danny Ledwith and Stephen Last have all re-signed, as has Dunedin goalkeeper Liam Little.
The group brings a wealth of experience which is spread throughout the field.
The signings have thrilled coach Paul O'Reilly, who estimated the group had played 500 top-level games among them.
Coughlan is arguably the key returner.
The 26-year-old striker was one of the league's top players in last year's national premiership.
He was sublime in scoring 13 goals from 18 games and has continued to find the net with ease for Cashmere Technical over the winter.
Having been with Southern for two years, he had been approached by several of the league's powers over the winter.
His decision to stay was significant for O'Reilly.
"There was huge interest around the league. Auckland City and Eastern Suburbs had extensive discussions with him to bring him in for OFC football,'' O'Reilly said.
"It's massive for us that he's committed. [He was] probably one of the best players in the league last year.''
O'Reilly said it had been feared that after the past two seasons' success, other clubs would come after Southern's players.
He did not want to stop his players progressing in their careers though.
Coughlan had been open in his wish to talk to the other clubs, but ultimately decided to stay.
The return of defenders O'Keeffe and Last, as well as midfielder Ledwith, is another boost.
The trio are among six Irishmen the club signed in 2016.
They have remained in the South and been very solid.
O'Keeffe, Southern's captain for the past two years, and Last both offer reliable pieces in a tough-to-break defence.
Ledwith's dangerous balls into the box and ability to shoot from long range give Southern a creative edge.
In Little, the side secures a quality keeper who has been involved with the club since the Otago United days.
Also re-signing are several youngsters.
Ben Deeley impressed through the second half of last season and has decided to stay.
He has withdrawn from Brown University, in the United States, where he was originally going to play.
Alex Cox, Rory Findlay, Stewart Catto and Tim O'Farrell return as well, all having had first-team experience after impressing in the youth team last year.
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