Born into a Neapolitan noble family of Spanish origin, he was made lieutenant of the Order on the death of Grand Master Giovanni Battista Tommasi in 1805, since the Order had been expelled from its traditional base on Malta and was now based in Catania.

Guevara Suardo distinguished himself as an admiral of the Order's naval fleet, using all his authority and firmness to prevent the Order's lands in Sicily being sold, as was planned during the reign of Joachim Murat, the new king of Naples.

During his lieutenancy he also unsuccessfully attempted to get the British government to return control of Malta to the Order, which they were unwilling to do even after the end of the Napoleonic Wars.

Guevara-Suardo was grateful for the offer but refused it as soon as it was made, since accepting it would insinuate that the Order was giving up its claims on Malta.

On his death in 1814 Guevara Suardo was buried in the convent church of Novaluce and succeeded as lieutenant by Andrea Di Giovanni y Centellés.