The Wall Honda driver needed to finish 12th or better in the finale to seal a maiden title.
However it proved to be a tense affair, title rival Will Brown (Melbourne Performance Centre Audi) romping to victory as D'Alberto clung on to just enough points.
In the end he was able to come home 11th to join Brown and Chaz Mostert on the TCR Australia winners' list.
"I'm speechless," said an emotional D'Alberto.
"We worked so fricking hard. This weekend was ultra tough, we had our hands tied with the car around here. The boys tried to pump me up all weekend, right until the end.
"I didn't know we had it until we stopped in parc ferme. It's been a big journey for myself, Honda and wall Racing. I'm so proud we've delivered a championship."
Effectively needing victory to win the title, Brown got an early gift on the opening lap when Dylan O'Keeffe (Garry Rogers Motorsport) slapped the wall at Griffins Bend while vying for the lead.
That helped him into third place behind Aaron Cameron (GRM Peugeot) and Nathan Morcom (HMO Hyundai).
By Lap 6 the complexion of the race had changed significantly after Cameron and Morcom got into each other while scrapping for the lead.
The contact was good news for Brown who was able to quickly clear Morcom, who left with damage, before going around the outside of Cameron at the Chase to take the lead.
At the same time D'Alberto slipped outside the Top 12, falling as far back as 14th as an upset looked to be on the cards.
D'Alberto wasn't done there, though, moving back into 12th on Lap 10. He was then helped further when Jordan Cox, another title contender, was forced to pit with a problem.
That moved D'Alberto up to 11th, which then became 10th when Ben Bargwanna (GRM Peugeot) stopped on Lap 13, prompting the first safety car period of the race.
When the race went green again on Lap 15 things immediately swung D'Alberto's way, with Bailey Sweeny (HMO Hyundai) diving past Brown to grab the lead.
Brown did find a way back through on the final lap to win the race, while D'Alberto slipped back behind fellow Honda driver to end up 11th, but that was still enough for D'Alberto to be crowned champion.
Sweeny finished the race second ahead of HMO Hyundai teammate Josh Buchan.
Cameron slipped back to fourth ahead of Lachlan Mineef (Purple Sector Audi) and Teddy Clairet (GRM Peugeot).
Luke King (Moutai Hyundai), Michael Caruso (Ash Seward Motorsport Alfa Romeo) and Clemente rounded out the Top 10.
