The 19-year-old defender enjoyed major success at both levels, helping Barcelona secure a second consecutive La Liga title before playing a key role in Spain's FIFA World Cup triumph in North America.
Cubarsi was also named FIFA Young Player of the Tournament after Spain conceded just one goal throughout their successful World Cup campaign.
Speaking in a video message broadcast by Tuttosport at the awards ceremony, Cubarsi expressed his delight at receiving the honour.
"I'm very proud to receive the award and I thank all the people that voted for me," he said.
"It's been a spectacular year and we're going for more."
Cubarsi becomes only the second defender to win the Golden Boy award since its introduction in 2003, following Matthijs de Ligt, who claimed the prize in 2018.
The Barcelona youngster believes defenders often struggle to receive the same recognition as attacking players because their contributions are less visible.
"It's harder for defenders to get recognition... we're less in the spotlight," he told Reuters.
"Perhaps our work isn't as visible because, at the end of the day, the forwards score lots of goals, provide assists, play a more attractive style of football, are more eye-catching."
Cubarsi also continues Barcelona's impressive record in the award, following teammates Gavi, Pedri and Lamine Yamal, who have all won the prize since 2021.
The Golden Boy award is voted for by journalists and recognises the best player aged under 21 competing in a top European division during the calendar year.
Alex Baena has admitted that Julian Alvarez's public comments about wanting to leave Atletico Madrid upset several of his teammates, with the midfielder insisting it was the striker's approach rather than his desire to move that caused frustration.
Ibrahima Konate has backed Kylian Mbappe to put his recent disappointments behind him, insisting the France captain is in a good frame of mind ahead of his return to international football.
Steven Gerrard believes Lamine Yamal has the potential to become one of football's greatest players, claiming the Barcelona teenager is already more advanced than Lionel Messi and Cristiano Ronaldo were at the same age.
Spain will be without Lamine Yamal and Mikel Oyarzabal for Thursday's Nations League clash against the Czech Republic after both players were ruled out through injury and illness.
