Florestan I (October 10, 1785–June 20, 1856) was Prince of Monaco from October 2, 1841 until his death. He was the second son of Prince Honoré IV, and succeeded to the throne upon the death of his brother, Honoré V.

Florestan was never prepared to assume the role of prince—he had been an actor in the Theatre de l’Ambigu-Comique— and the real power during his reign lay in the hands of his wife, Caroline Gilbert of Lametz . For some time, she was able to alleviate the difficult economic situation stemming from Monaco's new position as a protectorate of the Kingdom of Sardinia, rather than of France. The royal couple also attempted to meet local demands for greater democratization and offered two constitutions to the local population, but these were rejected, particularly by the people of Menton. When they saw that their efforted were doomed to failure, the handed power over to their son Charles (later Prince Charles III).

This was, however, too little, too late. Encouraged by the events of 1848, the towns of Menton and Roquebrune, revolted, and declared themselves independent. They had hoped to be annexed by Sardinia, but this did not occur, and the towns remained in a state of political limbo until they were finally ceded to France in 1861, under Charles III.

Despite his good intentions, by the time of Florestan's death in 1856, Monaco was a country divided with few prospects for financial prosperity. It remained for his heir to remedy the situation.