Baptised as a Catholic but raised in the Protestant faith by his mother Jeanne d'Albret, Queen of Navarre, he inherited the throne of Navarre in 1572 on the death of his mother. As a Huguenot, Henry was involved in the French Wars of Religion, barely escaping assassination in the St. Bartholomew's Day massacre, and later led Protestant forces against the royal army.

As a French "prince of the blood" by reason of his descent from King Louis IX, he ascended the throne of France upon the death of his childless brother-in-law Henry III in 1589. In accepting the throne, he found it prudent to abjure his Calvinist faith. Regardless, his coronation was followed by a four-year war against the Catholic League to establish his legitimacy. As a pragmatic politician (in the parlance of the time, a politique), he displayed an unusual religious tolerance for the time. Notably, he promulgated the Edict of Nantes in 1598, which guaranteed religious liberties to Protestants, thereby effectively ending the Wars of Religion. He was assassinated by Francois Ravaillac, a fanatical Catholic, and was succeeded by his son Louis XIII.

Considered as a usurper by Catholics and as a traitor by Protestants, Henry was hardly accepted by the population and escaped at least 12 assassination attempts. An unpopular king during his reign, Henry's popularity greatly improved posthumously. The "Good King Henry" (le bon roi Henri) was remembered for his geniality and his great concern about the welfare of his subjects. He was celebrated in the popular song Vive le roi Henri and in Voltaire's Henriade.

Achievements of his reign
During his reign, Henry IV worked through his faithful right-hand man, the minister Maximilien de Bethune, Duke of Sully, to regularise state finance, promote agriculture, drain swamps, undertake public works, and encourage education, as with the creation of the College Royal Henri-le-Grand in La Fleche (today the Prytanee Militaire de la Fleche). He and Sully protected forests from further devastation, built a new system of tree-lined highways, and constructed new bridges and canals. He had a 1200 metre canal built in the park at the Chateau Fontainebleau (which may be fished today) and ordered the planting of pines, elms, and fruit trees.

The king restored Paris as a great city, with the Pont Neuf, which still stands today, constructed over the Seine river to connect the Right and Left Banks of the city. Henry IV also had the Place Royale built (since 1800 known as Place des Vosges), and added the Grande Galerie to the Louvre Palace. More than 400 metres long and thirty-five metres wide, this huge addition was built along the bank of the Seine River, and at the time was the longest edifice of its kind in the world. King Henry IV, a promoter of the arts by all classes of people, invited hundreds of artists and craftsmen to live and work on the building's lower floors. This tradition continued for another two hundred years, until Emperor Napoleon I banned it. The art and architecture of his reign have become known as the "Henry IV style" since that time.

King Henry's vision extended beyond France, and he financed several expeditions of Pierre Dugua, Sieur de Monts, and Samuel de Champlain to North America that saw France lay claim to Canada.

Character
Henry IV proved to be a man of vision and courage. Instead of waging costly wars to suppress opposing nobles, Henry simply paid them off. As king, he adopted policies and undertook projects to improve the lives of all subjects, which made him one of the country's most popular rulers ever.

Henry is said to have originated the oft repeated phrase, "a chicken in every pot". The context in which he is reported to have said this is:

“    Si Dieu me prete vie, je ferai qu'il n'y aura point de laboureur en mon royaume qui n'ait les moyens d'avoir le dimanche une poule dans son pot!
(If God keeps me, I will make sure that no peasant in my realm will lack the means to have a chicken in the pot on Sunday!)”
This statement epitomises the peace and relative prosperity Henry brought to France after decades of religious war and demonstrates how well he understood the plight of the French worker and peasant farmer. This real concern for the living conditions of the "lowly" population – who in the final analysis provided the economic basis on which the power of the king and the great nobles rested – was perhaps without parallel among the kings of France. It also made Henry extremely popular with the population.

Henry's forthright manner, physical courage, and military successes also contrasted dramatically with the sickly, effete languor of the last Valois kings, as evinced by his blunt assertion that he ruled with "weapon in hand and arse in the saddle" (on a le bras arme et le cul sur la selle). He was also a great philanderer, fathering many children by a number of mistresses.

Nicknames
Henry was nicknamed Henry the Great (Henri le Grand), and in France is also called le bon roi Henri ("the good king Henry") or le vert galant ("The Green Gallant", for his numerous mistresses).[36] In English he is most often referred to as Henry of Navarre.