In his teens, Rivero's family moved to the Belgrano neighborhood, in the days where tango developed as a dancing phenomenon, but also as an ever more complex music form under the "ABC" of composers/directors Arolas, Bardi, and Cobián.

At the same time, the themes of tango lyrics evolved from light-hearted ribaldry into more complex stories delving on love and manly honor.

Rivero learned classic guitar and also trained as a singer; he had a deep bass-baritone voice that was one of his trademarks,[1] together with his huge hands (due to his acromegaly) that made him the butt of many jokes.

His three-year tenure there left no recordings (with his Bartók influences, Salgán was too "far out" for the general tango audience) but earned Rivero the respect of avant-garde and jazz musicians.

To make ends meet, Rivero also worked in a duo with fellow singer Carlos Bermúdez that recorded tangos in a more commercial vein for the Colombian market.

In 1947, Rivero was hired by Aníbal Troilo, who was having a stellar run of recordings with new hit songs, many of them in collaboration with lyricist Homero Manzi.

Guitar-only formations were used by countryside milonga artists, early tango singers, and even Carlos Gardel in his youth, but Rivero's 1950s recordings, during a period of total dominance by big orchestras, was a bold statement, which forever cemented his identification with the silent masculinity of the countryside, as opposed to the emphasis that "urban" tango put on stories of lost love.

His hospitality was enjoyed by many visitors to Buenos Aires, who went to Rivero's club to savor the tango music and dance in its full intensity.

Rivero hosted a TV show in the early seventies, which featured artists from the club (such as Beba Bidart), as well as lively dialog sprinkled with lunfardo.