Chile delighted the massed ranks of their exuberant fans by scoring the opening try of the match through prop Matias Dittus and Samoa needed the place-kicking of Christian Leali'ifano to creep ahead towards the end of the first half.
Tries from fullback Duncan Paia'aua and scrum-half Jonathan Taumateine immediately before and after halftime gave the Pacific islanders some breathing room and two tries from rolling mauls secured the bonus point.
"We've been waiting a long time for this game, and we talked a lot beforehand about the preparation for playing in big matches but nothing actually prepares you until you're out there in front of the crowd," Samoa captain Michael Alaalatoa said.
It was indeed a boisterous atmosphere with red-shirted Chile fans seemingly outnumbering their counterparts in the Bordeaux sunshine, willing their side on even as the early promise of an upset ebbed away.
Despite having two players sin-binned, the Chileans fought hard on the pitch and had the better of a scrappy final quarter until Samoa's reserve hooker Sama Malolo scored his second try with yet another rolling maul.
Chile's breakout star of the tournament has been their number 10 Rodrigo Fernandez, a running fly-half with a wicked sidestep who got Los Condores going with a slick show and go down the left that led to the early try for Dittus.
EARLY SCORE
It continued a theme from this tournament of the underdogs scoring first and fast.
But the Pacific Islanders were a constant threat with their direct, aggressive running and Chile conceded a string of penalties which Leali'ifano steadily converted into points.
The former Wallabies fly-half, eligible after World Rugby permitted players who stand down from internationals for three years to change allegiance, turns 36 at this tournament and has overcome leukaemia on the way to an unlikely second chapter in his test rugby career.
"Players who have joined Samoa through the eligibility amendment have strengthened our side, they're passionate about representing their Samoan heritage and mean I have a wider pool to select from," coach Seilala Mapusua said.
Leali'ifano provided the steady hand Samoa needed in what turned into a scrappy game as both sides wearied in the heat, and survived a monster tackle late on from Domingo Saavedra.
While the game was short on quality at times, it featured running rugby from both sides, tries, big hits and the haircut of the tournament in Samoan scrum-half Taumateine's bleached platinum blonde mullet.
Such a bold look demanded a performance to match and Taumateine delivered, bustling over in the corner after the break and flinging the ball into the crowd in delight with fans still taking their seats.
There is little substitute in rugby for raw power and Samoa's told in the end, their maul proving too much for Chile and setting a marker for their remaining opponents.
Samoa next face Argentina on September 22nd, while Chile play pool D frontrunners England on September 23rd, having already used up their best two shots at a shock first World Cup win.