Born in Aretxabaleta, Gipuzkoa into a noble family - his father was the Viscount of San Enrique - Ansaldo joined the army to fight in the Rif War. He remained until 1931 and the proclamation of the Second Spanish Republic, retiring with the rank of major.
A member of Ramiro de Maeztu's Acción Española, Ansaldo was a devoted follower of the monarchist general José Sanjurjo. By 1932 Ansaldo's holiday home in Biarritz was playing host to various leading monarchists, and this group grew close to the Unión Militar Española, which was planning to overthrow the republican government. He was also a founder and leading member of Renovación Española, another group dedicated to restoring the monarchy in the Alfonsist tendency.
Ansaldo visited Fascist Italy the same year in an attempt to drum up support for the conspiracy,particularly from Italo Balbo, with whom he had contact. He and José Calvo Sotelo would make a return visit the following year,although neither trip produced any concrete results. However in Ansaldo's efforts in this and other areas did raise a total of 3 million pesetas to fund the conspiracy.
In 1934 Ansaldo was at the centre of a coup plot when it was arranged for him to fly Sanjurjo back from exile in Portugal. The plan was for Sanjurjo to link up with Juan Yagüe and to lead a coup. However whilst the plotters waited at Pedro Sainz Rodríguez's house word came through from Francisco Franco that the time was not right and so Ansaldo's mission was abandoned. He was again called into action in July 1936 when it appeared that Franco was wavering in his command and General Emilio Mola ordered Ansaldo to pick up Sanjurjo from Portugal and fly him to Morocco to relieve Franco of his command. The plan was again abandoned however when Franco returned to action a few days later.
Although a monarchist, Ansaldo was drawn to the violent action and adventurism of fascism and as such maintained close links with such groups. He helped to fund both the Juntas de Ofensiva Nacional-Sindicalista and the Movimiento Sindicalista Española in the early 1930s, personally favouring the latter movement, which owed more to Blackshirts of Italian fascism in its character. With both these groups floundering he turned his attentions instead to the Falange and formally joined the group in early 1934. He became jefe de commandos and took charge of the so-called Falange de la Sangre militia squads engaged in responding to the leftist attacks. In this capacity Ansaldo became noted for his extreme violence, not only preventing any socialist activity in Madrid on May Day 1934 but also for his proclaimed intention of killing any of his own men suspected of betraying the Falange. Nonetheless, Ansaldo did not abandon his earlier monarchist principles and hoped to turn the Falange to that ideology. To this end he conspired to edge Primo de Rivera out of his position of leadership, something that led to his expulsion from the movement in 1934. He went into voluntary exile in France after this setback, although continued to be closely involved in monarchist conspiracy from his new base.
In late July 1936 Ansaldo was finally called by General Mola upon to transport his mentor from his exile in Estoril. Flying only a small biplane, the flight hit difficulty when Sanjurjo, who was a very heavy man to begin with, insisted on carrying a large amount of luggage with him. Unsuited to being so heavily weighed down the plane crashed just after take-off, killing Sanjurjo. Ansaldo, however, survived the crash, despite suffering extensive injuries. The incident was to Franco's advantage as one of his two main rivals to power, the other being Mola, was eliminated.
Ansaldo returned to action during the Civil War, serving with the nationalist air force in the northern campaign. Following the Civil War Ansaldo continued his career in the Spanish Air Force and had risen to the rank of colonel by 1940. He would also serve as an air attaché to the United Kingdom and then Vichy France. By this time, Ansaldo had become firmly estranged from Franco and was involved in a futile conspiracy with Eugenio Vegas Latapie to restore the monarchy. He launched further clandestine initiatives with Alfredo Kindelán and other monarchists when it became clear that Franco had no intention of restoring the monarchy at that time.
He was exiled from Spain in 1945 after Franco launched a purge of leading monarchists initially to Portugal before returning to France in 1947. His disillusionment with the Franco regime was reflected in his 1951 memoir ¿Para que... (For What?) in which he criticised El Caudillo for betraying the war against the republicans by not restoring the monarchy. He died in Ville-d'Avray in 1958.