[1] Louis Grimaldi was the elder son of Prince Hercule of Monaco and Genoese noblewoman, Maria Aurelia Spinola.

His younger siblings were Maria Ippolita Grimaldi (wife of Carlo Emanuele Filiberto de Simiane, Prince of Montafia), Giovanna Maria Grimaldi (wife of Andrea Imperiali, Prince of Francavilla), and Teresa Maria Grimaldi (wife of Sigismondo III d'Este, Marquis of San Martino).

In 1662, Louis succeeded his grandfather Honoré II as Prince of Monaco.

In 1666 he distinguished himself at the Four Days' Battle between the English and Dutch fleets.

There on 19 December he presented the insignia of the Order of the Holy Spirit to James Louis and Alexander Benedict Sobieski, the two sons of King John III of Poland.