The out-of-contract finisher scored his 47th goal for the Clarets on his 247th appearance when beating Aston Villa goalkeeper Emi Martinez from the spot on Thursday evening.
The ex-Brighton and Hove Albion forward, a true cult hero at Turf Moor, arrived more than eight years ago to boost Burnley's Championship promotion chase.
Sean Dyche's first cash signing has since played 199 times in the top flight and played all-but one of the club's six ties in the Europa League at the start of 2018.
With the Clarets needing to match Leeds United's result at Brentford to guarantee their safety, Barnes said: "It would mean a massive amount [to keep Burnley in the Premier League]. The club have shown faith in me through everything and hopefully I can go and give that back in my last game.
"This group of players is second to none. There's an abundance of quality and a know-how to stay in this league. Hopefully we're lucky enough to do that. We'll fight right until the end. Sunday is a massive game for us. Hopefully we can get the three points that keeps us in the league."
The 32-year-old scored his first goal in 15 months at Villa Park, having last netted in a 1-1 draw at home to Fulham, as he cancelled out Ola Aina's fortuitous opener.
He kept his cool in front of a packed Holt End to tuck his spot kick away just before half time after Emiliano Buendia had tripped Maxwel Cornet inside the box.
Goalkeeper Nick Pope then preserved a point for the visitors with a string of saves — including a world class stop to keep out a Bertrand Traore header — after Emiliano Buendia had steered home John McGinn's delivery early in the second half.
"It's been a long time coming," he said. "It's been a difficult season for me with not being able to play, but I've just had to wait for my moment and luckily enough I got that. I just want to give everything back for the faith that's been shown in me.
"It's not just about me, though, that's what I'm there to do. I'm there to score. It's not been good enough this season, from all of us, but Popey has kept us in the game and he's the hero tonight. We move on now and it's in our hands heading into Sunday so hopefully we can get it over the line."
Meanwhile, Barnes expressed his disappointment and frustration in the inconsistencies shown in the decision-making of Premier League officials.
The former Plymouth Argyle man was penalised for handball at the Tottenham Hotspur Stadium at the weekend when a Davinson Sanchez flick brushed his arm.
But the away side had no such luck against the Villans when a VAR check returned a negative verdict when the ball had struck the outstretched arm of Lucas Digne.
Barnes concluded: "It's incredible. It clearly hits his hand, it hit mine at the weekend because my arm's in an unnatural position due to a foul. They [Spurs] went on to miss a great chance and nobody in the stadium thought anything about it. We've set up for a goal kick then he [Kevin Friend] has pulled it back.
"It's an absolute shambles. Tonight was exactly the same so they need to clear this up. I don't know why he [Paul Tierney] doesn't even go over to view the monitor. That's the frustrating thing for us and you could see because we're all complaining.
"They're no different; if anything, this one is worse. We're trying to score whereas, with mine, the ball was going up in the air after skimming my arm. There's something every week."