t age 14, in 1907, he started in tango playing as soloist in movie theaters of that time in Montevideo, when sound movies were not yet known, and as leader of tango quartets later. For that reason he was called «the father of tango in Uruguay» and «the dean of the Uruguayan pianists». Fronting one of those quartets, he cut the first recording of "La cumparsita" in the history of this immortal tango: in Buenos Aires, May 1917, disc RCA-Victor N° 69.579, with the Alonso-Minoto Orchestra. With the latter he played in cafes of Buenos Aires.

In 1915 he wrote his first composition, the country polka "La ruralista", but as he was a tango man, for the latter genre he released his best numbers such as "La cachimba", "Nobleza criolla", "Tres de oro", "Alma gaucha", "Leña seca", "La alborada", "Bachicha", "Pebetita", "Puro cuento" which bears festive words by Paco Ruiz París and was recorded by Charlo in his best period and, among several more, "Como la Mosca" which was committed to record by Carlos Gardel.

«It’s always worthwhile to repeat –once this composer said- that it would be very difficult to find again an individual like Gardel. Noble, unselfish, nice, supportive, in other words, a friend. And because of that if he knew that a friend of his was a songwriter he felt obliged to commit to record his oeuvre.

«I met him in 1915 at the time of his first appearances in Montevideo with Razzano, but for many years we did not talk about my tangos. The last time I talked to him was in 1929 and soon he went to Europe; on his comeback and when he was in Montevideo, Aubriot Barboza delivered him "Como la mosca" and fifteen days later it was recorded».

He published a booklet about "La cumparsita".

Alonso was born in Montevideo on April 12, 1893 and there he died on September 27, 1974.