Ferreira beat fellow Brazilian Gabriel Medina to take the season-ending Pipe Masters with five spots remaining for male surfers at the sport's Olympic debut.
The conclusion of the 2019 surfing season was one of the most dramatic in history.
The Pipe Masters was a showdown for the ages with Italo Ferreira taking victory to become WSL world champion for the first time.
It was a fairytale finale for Brazilian fans, with the title going down to the wire.
Ferreira defeated Gabriel Medina in the final to deny his fellow Brazilian a third world crown.
The duo also booked their places for surfing's Olympic debut on Tsurigasaki Beach with competition scheduled to start on 26 July.
Fifteen of the world's best male surfers have now punched their tickets for Tokyo 2020.
There were thrilling battles for the final tickets to Tokyo from the WSL.
In the end, John John Florence took the last men's spot over 11-time world champion Kelly Slater.
The Hawaiian native joins Kolohe Andino who provisionally qualified for Tokyo in October.
Owen Wright and Julian Wilson claimed the two Australian men's places with Michel Bourez joining Jeremy Flores to ensure France will have two challengers in Japan.
The completion of the iconic contest off the north shore of Oahu, Hawaii locks in the 10 male surfers who have provisional Olympic spots through the 2019 WSL Championship Tour
With a total of 20 men competing at surfing's Olympic debut next year, five spots remain open for male athletes after five berths were decided at the Pan American Games and September's 2019 ISA World Surfing Games.
These will be allocated at the 2020 ISA World Surfing Games in May, at a location, yet to be determined.
It came down to the wire but in the end the young star prevailed with John John Florence going to Tokyo at Kelly Slater expense.
The 27-year old make a remarkable return to competition at the Pipe Masters having missed more than half the season with a ruptured ACL knee ligament.
The two-time world champion needed to score more points than Slater to take the second USA men's spot, and did so to leave the 47-year-old's future in the balance.
Slater suggested to Olympic Channel that failing to qualify for surfing's Olympic debut could mean the end for his 29-year professional surfing career.
But. speaking to the WSL during the Pipe Masters broadcast, he said, "I might have to do one more lap."
Tokyo will have the best of the best in the water.
Qualifying from the WSL Championship Tour are Ferreira, Medina, Florence, Andino, Wright, Wilson, Bourez and Flores plus South Africa's Jordy Smith and Japan's very own Kanoa Igarashi.
Lucca Mesinas will represent Peru after earning qualification through the Pan American Games in Lima, Peru, in July.
The 2019 ISA World Surfing Games saw Frederico Morais from Portugal, Morocco’s Ramzi Boukhiam, New Zealand’s Billy Stairmand, and Japan's Shun Murakami earn their places too.
The 15 confirmed male surfers in Tokyo next year are:
Qualified via the 2019 World Surf League Championship Tour:
Gabriel Medina (Brazil)
Italo Ferreira (Brazil)
Kolohe Andino (United States)
John John Florence (United States)
Owen Wright (Australia)
Julian Wilson (Australia)
Michel Bourez (France)
Jeremy Flores (France)
Jordy Smith (South Africa)
Kanoa Igarashi (Japan)
Qualified through the 2019 Pan American Games:
Lucca Mesinas (Peru)
Qualified through the 2019 ISA World Surfing Games:
Frederico Morais (Portugal)
Ramzi Boukhiam (Morocco)
Shun Murakami (Japan)
Billy Stairmand (New Zealand)