The two-time defending provincial champions also maintained their status atop the competition standings although competition points were of secondary importance as they ended Southland's memorable six-match shield tenure despite being dominated in key facets.
A Colin Slade penalty six minutes from fulltime heralded the beginning of Canterbury's 14th era with the shield although a pulsating match hinged on two key moments earlier in the final quarter.
Southland twice turned down kickable penalties in a bid to score a converted try and level the scores at 23-23 but were thwarted by Matt Todd, who dispossessed All Blacks halfback Jimmy Cowan in the shadow of the goalposts.
The flanker's intervention was the catalyst for a 100m counter-attack initiated by Sonny Bill Williams and almost culminated in a try to the All Black-in-waiting.
From then on Southland struggled for field position after they monopolised territory and possession for vast tracts of the game.
Canterbury had to settle for 32 percent of the ball and used it wisely, especially when filched from a Southlander's grasp.
Slade, who nailed a perfect six from six goalkicks, also contributed the killer try in the 52nd minute, which was an illustration of Canterbury's ability to strike seemingly from nowhere.
The Highlanders-bound first five-eighth, who contributed 21 points, scampered over while his opposite Robbie Robinson was being treated for a chest injury after trying to stop a rampaging Robbie Fruean.
Southland, who had seen off the notable challenges of neighbours Otago and Auckland before a captive audience, predictably stayed true to their no frills approach when facing a stiff breeze in the first half.
In a trend that continued throughout the game, Canterbury were largely confined to defensive duties until the 17th minute when James Wilson's grubber kick cannoned off Williams, who effortlessly scooped up the ball and angled to the sideline before providing wing Telusa Veainu with a saloon passage to the line.
Canterbury's expertise in capitalising on Southland errors was again evident when a botched lineout throw and barging run from impressive No 8 Nasi Manu led to Slade's second penalty - and a 13-3 lead when Cowan infringed at the breakdown.
Playing his first part in Southland's shield reign, Cowan was fortunate not to cost his team more points when a kick out on the full allowed Canterbury to threaten until wide-ranging lock Isaac Ross lost control of the ball close to the line.
Slade pushed Canterbury's advantage into double figures on the half hour when skipper Jamie Mackintosh was penalised but from then on Southland turned their dominance into points.
Robinson goaled a penalty, reward after wave after wave of Southland attack seven minutes before the break, and they maintained the rage after being stymied by television match official Doug Rodgers' borderline call.
After a lengthy adjudication Rogers ruled Tony Koonwaiyou was in touch when he flung a miracle ball in for John Hardie to dive over in the corner.
Undeterred by the 38th minute setback, Tim Boys stole Canterbury's lineout possession and after 12 phases Koonwaiyou flicked a legitimate pass to No 8 Kane Thompson to trim Canterbury's lead to 16-13 at the break.
Canterbury will defend the shield for the first time against Counties-Manukau in Christchurch next Saturday.
