The 22-year-old dummied his way through in the 76th minute after delivering a brilliant performance in the absence of injured veteran Kieran Foran at Cbus Super Stadium.
Sexton kicked superbly throughout the match and had a hand in the Titans' only try of the first half in a display of grit and class.
Last year he played 19 games in a badly beaten side and was overlooked at the start of the season before answering the call on Sunday when his team needed him.
Dragons captain Ben Hunt looked to have won it in the 73rd minute when he gave his side the lead but the Titans dug deep to move into the top eight.
The scoreline was 8-all at halftime after both sides saved tries and bombed them with regularity in front of 12,452 fans.
Dragons back-rower Jaydn Su'A was penalised for starting a fracas when he raced in to give Titans captain Tino Fa'asuamaleaui a shove after a heavy tackle on Dragons fullback Tyrell Sloan.
The subsequent melee was full of feeling, a reflection of how desperate both sides are to get themselves into finals contention in 2023.
Dragons winger Mikaele Ravalawa put his hand up to bulldoze his way over from 15m early in the second half after vision from Hunt gave him space.
The best player on the field, Titans winger Phil Sami who ran for a stunning 275m, repeated the dose with a charge of his own.
Su'A was put on report for a hip-drop tackle on Titans half Tanah Boyd and then helped Ravalawa stop Boyd from scoring.
But it was the Titans who saved multiple tries at the death before Sexton's heroics.
Dragons prop Francis Molo was sin-binned for high shot on Moeaki Fotuaika in the fourth minute but his teammates scrambled while he was off to stop winger Alofiana Khan-Pereira scoring twice.
They bombed three tries of their own as both teams failed to ice their chances.
Dragons centre Zac Lomax is an aerial specialist and made a determined, diagonal run to snaffle a pinpoint Ben Hunt bomb and score the first try.
With AJ Brimson out with a calf injury, his electrifying replacement at fullback Jayden Campbell took it upon himself to ignite the Titans with an old-fashioned run-around with Sexton..
Former Leeds Rhino skipper Kruise Leeming came on with 30 minutes to go and in doing so became the first player born in Eswatini, formerly Swaziland, to play in the NRL.
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