[1][2] In 1862, the 18-year-old Alonso emigrated to Havana, when the country was under the sovereignty of the Spanish Empire, where he remained working until 1881 as a commercial intermediary between Cuba and the metropolis (Spain).

[2] In Cuba, he married Eloísa Giménez-Cuenca (1860–1935), daughter of an important military man from Matanzas.

[1][2] The couple had six children Pedro, Salvador, Rodrigo, Antonio, Mauro, and Guillermina Alonso Giménez-Cuenca, who married Eduardo Martínez Vázquez, with whom she had Eduardo Martínez Alonso [es],[1][2][3] who went on to become a doctor known for his humanitarian work during the Spanish Civil War and Second World War.

It is in Vigo where he established contact with the canning industry and in 1886, he began his own initiative, starting with the help of his partner Benito Albela and from 1890 onwards alone.

[2][3] His first-born son Pedro, suffering from health problems, did not join the business, and his only daughter Guillermina did not receive the inheritance, so the business saga was continued by Rodrigo, Antonio, Mauro, and Salvador, who in 1918 created the Antonio Alonso-Hijos company.