Johnny Cardoso

Internacional

Cardoso made his professional debut with Internacional in a 3–1 Campeonato Brasileiro Série A win over Atlético Mineiro on September 15, 2019. He scored his first goal for Internacional on March 4, 2021, in a 2-2 draw against Pelotas, in a match valid for the Campeonato Gaúcho (Rio Grande do Sul's state championship).

Cardoso suffered some injuries during the 2023 season, but finished as a starter in the team managed by Eduardo Coudet. That year, the midfielder played in 49 matches, scored two goals and provided two assists. He departed the club at the end of the year. For Internacional, he played 144 matches, scored seven goals, gave five assists and left without winning any titles.

Real Betis

On December 27, 2023, Cardoso moved to La Liga club Real Betis on a reported five-year contract worth $6.3 million in exchange for six million euros for 80% of his rights. On January 21, 2024, Cardoso made his debut for Betis, starting and playing 73 minutes in a league match against FC Barcelona which finished in a 2–4 loss. As part of Giovani Lo Celso's transfer from Tottenham Hotspur to Betis in 2024, Tottenham acquired a non-mandatory €25 million purchase option for Cardoso in summer 2025. On February 4, 2025, Cardoso extended his contract with Betis until 2030. This season he was a regular starter with 46 matches played, scoring four goals and providing one assist. He helped the team finish runner-up in that season's UEFA Conference League, losing the final 4-1 to Chelsea. Cardoso also helped Betis qualify for the UEFA Europa League after finishing in sixth place in that season's La Liga.

Atlético Madrid

On July 16, 2025, Cardoso moved to Atlético Madrid on a five-year contract worth a reported €30 million. On February 24, 2026, he scored his first goal for the club in a 4–1 win over Club Brugge in the Champions League knockout play-offs.

As he was born in the United States to Brazilian parents, he was initially eligible to represent both Brazil and the United States, Cardoso received his first call-up to the United States under-23 training camp in October 2019. He received his first call up to the senior United States squad for matches against Wales and Panama in November 2020.

Cardoso was subsequently called up again to the United States under-23 team for the 2020 CONCACAF Men's Olympic Qualifying Championship, in which the United States failed to qualify for the Olympics.

In June 2023, the midfielder was called up again by the United States to compete in the final phase of that year's CONCACAF Nations League. On that occasion, the USA were crowned champions in a final against Canada, with Johnny entering the game during the second half.

In May 2026, Cardoso underwent surgery for an ankle injury, ruling him out of the 2026 FIFA World Cup on home soil.