The Brazilian took the honours in a tense final to become the first South American to win an ASP World Tour title.
“This is the most important event on tour to me,” De Souza said. “Guys like Andy Irons, Kelly Slater, my hero Mick Fanning, they have all rung the Bell.
"I have been coming here a lot of years. I love the place. It has been a tough time for me recently. I started 2013 without a sponsor for the first time in many years.
"I had to believe in myself that a company would believe in me and one did. I have to say thanks to Pena for believing in me.
"I have a lot of people to thank, but all I want to do right now is ring the bell.”
In clean three-to-five foot waves at Bells Beach, De Souza ensured he rose to fourth in the world rankings heading into the season's third event in Brazil.
“Next stop is at home in Brazil,” De Souza said. “I feel comfortable at home, but there is also pressure to perform. I am going to enjoy this win, recharge for the next one and hopefully I can keep it going.”
For Young, a runners-up place was the best finish of his career.
“It was a huge event for me,” Young said. “Just to be in the field is a dream for me. I’ve looked up to the surfers in this event my whole life.
"The event has such a history behind it and I was honestly just excited to be here. Making the Final, I don’t even have words for it. Of course I wanted to win it. I want to ring the bell as much as anyone else on tour. "
Rip Curl Pro Bells Beach final result
1 – Adriano de Souza (BRA) 16.26
2 – Nat Young (USA) 15.83
Rip Curl Pro Bells Beach semi-final results
SF 1: Nat Young (USA) 15.10 def. Taj Burrow (AUS) 13.43
SF 2: Adriano de Souza (BRA) 18.44 def. Jordy Smith (ZAF) 18.40
Rip Curl Pro Bells Beach quarter-final results
QF 1: Taj Burrow (AUS) 15.50 def. Kai Otton (AUS) 14.50
QF 2: Nat Young (USA) 17.27 def. Willian Cardoso (BRA) 14.83
QF 3: Adriano de Souza (BRA) 14.33 def. Mick Fanning (AUS) 13.76
QF 4: Jordy Smith (ZAF) 16.77 def. Filipe Toledo (BRA) 13.20
ASP World Tour top six
1. Kelly Slater (USA) 11,750 pts
2. Mick Fanning (AUS) 11,700 pts
2. Taj Burrow (AUS) 11,700 pts
4. Adriano de Souza (BRA) 10,500 pts
5. Joel Parkinson (AUS) 9,750 pts
6. Nat Young (USA) 9,750 pts