He was the eldest son and heir of Louis II of Anjou and Yolande of Aragon.
The throne of Aragon fell vacant in 1410 (Louis was then 6 years old) when king Martin I of Aragon died. Louis' mother Yolande was the surviving daughter of sonless King John I of Aragon, Martin's predecessor. They claimed the throne of Aragon for the young Louis.
However, unclear though they were, the succession rules of Aragon and Barcelona at that time were understood to favor all male relatives before any female (this is how Yolande's uncle, Martin of Aragon, inherited the throne of Aragon). Martin died without surviving issue in 1410, and after two years without a king, the Estates of Aragon by Compromise of Caspe in 1412 elected Infante Ferdinand of Castile as the next King of Aragon. Ferdinand was the second son of Eleanor of Aragon and John I of Castile. The family however had secured some Aragonese lands in Montpellier and Roussillon.
Yolande and her sons regarded themselves as heirs of higher claim and began to use the title of Kings of Aragon. From this "inheritance" forward (Aragon added to other Angevin titles), Louis and Yolande were called the King and Queen of Four Kingdoms, those four being Sicily (including Naples), Jerusalem, Aragon, and Majorca. Of those, only the mainland part of Sicily was ever directly held by Louis, and only briefly. Louis also had claims on the title Latin Emperor, which his grandfather Louis I had purchased in 1383, but he never appears to have used this title.
Pope Martin V invested Louis III on 4 December 1419 as King of Sicily (Naples). This was in contrast with the will of the childless and aged queen of the Italian kingdom, Joanna II, who had adopted Alfonso V of Aragon as her heir. In 1420 Louis disembarked in Campania and besieged Naples, but had to flee at the arrival of an Aragonese fleet. Alfonso entered the city in 1421 and Louis lost the support of the Pope, tired by the costs of the war. However, when the relationships between Alfonso and the queen suddenly worsened after the arrest of Joanna's lover and prime minister, Gianni Caracciolo, the queen moved to Aversa where Louis joined her. He was adopted and named heir in lieu of Alfonso, giving him the title of Duke of Calabria. When Alfonso had to return to Aragon, the kingdom was pacified. Louis moved to his feudal possession in Calabria, where he lived with Margaret of Savoy, daughter of Amadeus VIII, Duke of Savoy. They had no children.
Louis could never become king effectively, as he died of malaria at Cosenza in 1434. After Joanna's death the following year, his brother René of Anjou was named King of Naples.