After going down to 12 men, following Ben Flower's red card, Wigan scored 21 unanswered points to triumph.
The Warriors have lost the past two Super League deciders at Old Trafford.
"We will take a lot of confidence coming into the back end of the year when confidence is important going into big games," Smith said.
Victory when the Catalans Dragons visit the DW Stadium next week would guarantee Wigan a home semi-final, while their hopes of clinching the League Leaders' Shield are slim as Warrington travel to second-placed Hull FC.
Warrington only need a draw to win the first piece of Super League silverware this season.
"We are looking just to win the game next week. Whatever comes of it, being first or second, gets us a home semi and that is what we want," Smith told BBC Radio Manchester.
"We want to get to Old Trafford and want to win. We've had a disappointing couple of years, and it is all about progressing now and putting in a performance next week."
If Wigan do reach the final for a fourth successive season, they may be without Flower after his elbow on Declan Patton saw him sent off with 23 minutes remaining on Friday.
It was the prop's first dismissal since receiving an early red card in Wigan's Grand Final defeat by St Helens in 2014.
A man down and with the League Leaders' Shield being made ready for presentation to Wolves, the visitors produced a remarkable turnaround from 28-14 down in the second half.
Josh Charnley touched town twice and Lewis Tierney completed a brace of his own before Smith edged Wigan ahead with a drop goal. Anthony Gelling's late try put the result beyond doubt.
"As soon as we got the first try when Benny got sent off I think the belief was there to go on and do something special," Smith said.
"When you come to stadiums like this and get results like that, it gives you a massive lift."
Wigan have the confidence to go on and win the Super League Grand Final after overcoming leaders Warrington on Friday, says half-back Matty Smith.