Bunting arguably played his best darts of the tournament after beating Jonny Clayton and Gerwyn Price earlier in the night before saving his best till last to beat the reigning champion.
Impressively storming into a 4-1 lead with five maximums, the Bullet served up some world-class darts to stun Humphries in the opening five legs.
Cool Hand - who beat Michael van Gerwen and Luke Littler to reach the final - then produced a sensational 132 checkout in leg six (treble 19, 25, bull) to threaten an unlikely comeback.
However, Bunting continued to throw incredible tungsten and almost ended the night in style with six perfect darts before finishing the match on double 8.
Reflecting on a brilliant finish to the Premier League, the world No. 9 admitted that he wants to be a part of this competition for "years" to come.
"People wrote me off, said I shouldn't be in the Premier League, but I finished fifth and had two nightly wins. I dug deep tonight," Bunting told Sky Sports.
"There was pressure off, but sometimes you see people in this position think it doesn't matter. I really wanted to win and make a statement.
"I want to be in the Premier League for years to come, and that was a massive statement from me."
Bunting blasts past Clayton and Price
Bunting kissed goodbye to his faint top four hopes on night 15 after being whitewashed 6-0 by Humphries. But instead of throwing in the towel and accepting disappointment, he showcased immense professionalism to produce some explosive darts in Sheffield.
Beginning the night with an impressive 6-3 victory over second-place Clayton, the Bullet recorded a 102 average, three maximums and 46 per cent (6/13) on checkouts, with a classy 102 finish in the middle.
The Liverpool-born arrowsmith then raised the bar even higher in a 6-3 semi-final triumph over Price. Bunting made a poor start to the game and would have gone 3-0 down if the Welshman had converted one of his five darts at double.
A spectator in the crowd then angered Price in leg four, causing a long pause in play. Once he was removed, the Iceman was unable to keep his cool in the decisive moments, and Bunting took charge of the contest to win six of the last seven legs.
The 41-year-old played at a notably quicker rhythm and, as a result, produced an exceptional swansong. Including an eye-catching 161 finish in leg seven, Bunting ended the match with a ton-plus checkout in each of the final three legs, completing his demolition of Price with a 104 finish (20, treble 16, double 18) to book his place in the final.
Premier League night 16 results:
Quarter finals
Jonny Clayton 3-6 Stephen Bunting
Gerwyn Price 6-2 Gian van Veen
Luke Littler 6-5 Josh Rock
Luke Humphries 6-5 Michael van Gerwen
Semi-finals
Stephen Bunting 6-3 Gerwyn Price
Luke Littler 1-6 Luke Humphries
Final
Luke Humphries 3-6 Stephen Bunting