Needing just a draw to retain the Shield, Victoria elected to continue batting into the fifth day, setting South Australia a massive target of 524 from 69 overs at a required run rate of 7.6 an over.
The Redbacks faced a challenging final-day on the Traeger Park pitch from the outset, and had reached 6-236 when play was abandoned with 20 minutes remaining.
It is the Bushrangers' third straight Shield title, a feat not achieved since Queensland in 2002 and never previously by Victoria in their 125-year history.
However, it took a defiant unbeaten century from Travis Head to hold the innings together and deny the Bushrangers the extra satisfaction of victory.
Head's second century of the campaign came off 125 deliveries, before the skipper ended on an unbeaten 137 from 172 balls.
The Redbacks started slowly as they were 2-28, and then 4-118 at tea, but ultimately denied Victoria a win in the season finale.
In-form Victorian paceman James Pattinson took 2-4 in his opening spell, with Jake Weatherald and Callum Ferguson both dismissed for two.
Player of the match Jon Holland was thrown the ball in only the fourth over, but the spinner was unable to reprise his first-innings heroics that had reaped a match-defining seven wickets.
Leg-spinner Fawad Ahmed briefly threatened to run through the SA middle order late, but Head and Alex Carey (45) remained resolute.
Earlier, Victoria were subdued in adding 45 runs during the first hour before being bowled out for 323, with Dan Christian falling for 58 and wicketkeeper Seb Gotch for 48.
The match saw Chadd Sayers add another whopping seven wickets to his total of 62 for the season - five behind Colin Miller's all-time record of 67, and three behind Shaun Tait's 65.
Alex Carey also took his 59th catch as he became the all-time record holder for most dismissals in a series, surpassing Wade Seccombe's 58.