He founded his first conjunto in Havana in 1957. In the 1950s, Alonso sang with Benny Moré and Fernando Álvarez, a trio popularly known as  "The Three Musketeers".
In the 1950s, Alonso formed his initial conjunto in Havana. During the 1950s, Alonso performed with Benny Moré and Fernando Álvarez, a trio widely recognized as "The Three Musketeers."