Opening batter Smith (65 runs off 43 balls) was the Sixers' top-scorer for the fifth time in as many games this season, taking charge after Moises Henriques lost the bat flip at the SCG.
Smith shrugged off the loss of opening partner Babar Azam, who abruptly left for Pakistan national team duties on Thursday, to power the Sixers (8-198) to their highest score when batting first in a finals match.
Hamstring tightness ruled Hurricanes captain ruled Nathan Ellis out on Friday afternoon and the quick will miss Sunday's tournament decider against Perth should the reigning champions qualify.
Rishad Hossain (2-33) finally had Smith's number during the power surge, where the right-hander had done his best work making a century last time out in Sydney.
Smith mistimed his reverse sweep and was bowled in a 13th over that ended with Henriques holing out on 19.
Earlier, Smith kick-started the Sixers' innings with consecutive fours off Riley Meredith (3-52) in the second over.
The lone six of Smith's innings flew into the Brewongle Stand off Will Prestwidge, though not quite as high as the shot that landed on the roof of that same grandstand in Smith's last game at the SCG.
Smith mined the area behind the stumps, particularly past third man, and brought up his third half-century of the tournament with a cut shot that bounced once for four past backward point.
Billy Stanlake (2-46) was key early, dismissing new opener Daniel Hughes (13) and No.3 Josh Philippe (15) before they could forge meaty partnerships with Smith.
But not even the rangy Hurricanes quick was immune to Smith, clubbed for four off consecutive balls early in the power surge.
In his 100th BBL game, Babar's replacement Hughes flicked to a diving Tim Ward but his modest total was still bigger than seven of his predecessor's 12 this summer.
Hughes hit one six, more than Babar could manage in any of his last six innings for the Sixers.
The start to Friday's game was briefly delayed as magenta-coloured smoke lingered over the SCG following pre-match pyrotechnics.