Aged just 16 years old he made his Nationalliga A debut with their first team, on 6 March 1955, and he scored his first goal with them during the same game.
They ended the league season in seventh position, but in the Swiss Cup LCdF advanced to final, which was played in the Wankdorf Stadium on 23 April 1961.
In the winter break of Basel's 1963–64 season he returned to his former club under head coach Jiří Sobotka.
A well-documented curiosity was the fact that during the winter break of their 1963–64 season the team travelled on a world tour.
This saw them visit British Hong Kong, Malaysia, Singapore, Australia, New Zealand, French Polynesia, Mexico and the United States.
First team manager Jiří Sobotka together with 16 players and 15 members of staff, supporters and journalists participated in this world tour from 10 January to 10 February 1964.
Club chairman, Lucien Schmidlin, led the group, but as they arrived in the hotel in Bangkok, he realised that 250,000 Swiss Francs were missing.
After 88 minutes of play, with the score at 1–1, referee Karl Göppel awarded Basel a controversial penalty.
Subsequently, after the 2–1 lead for Basel the Lausanne players refused to resume the game and they sat down demonstratively on the pitch.
Frigerio was nominated in the Swiss national squad for the 1962 FIFA World Cup, but he remained as an unused substitute on the bench in all three games.
He played his debut for the country on 3 May 1967 as Switzerland lost their home game 21 to Czechoslovakia and this was to remain his only appearance for the team.