His full title for the last three decades of his reign was "James, by the grace of God, king of Aragon, Valencia, Sardinia and Corsica, and count of Barcelona" (Latin: Iacobus Dei gratia rex Aragonum, Valencie, Sardinie, et Corsice ac comes Barchinone).

[1] He succeeded his father in Sicily in 1285 and his elder brother Alfonso III in Aragon and the rest of the Spanish territories, including Majorca, in 1291.

Two years later rom Pope Boniface VIII returned the island to the king of Majorca along with rights to Sardinia and Corsica.

On 20 January 1296, Boniface issued the bull Redemptor mundi granting James the titles of Standard-bearer, Captain General and Admiral of the Roman church.

By a peace treaty with Charles II of Anjou in 1296, he agreed to give up Sicily, but the Sicilians instead installed his brother Frederick on the throne.

In order to achieve this goal, and assisted by his Admiral Don Bernat de Sarrià, Baron of Polop, he formed an alliance with the enemies of the adolescent king of Castile, Ferdinand IV.

In 1313, James II granted administrative and political autonomy to the Aran Valley, the legal details of which are described in a Latin manuscript called the Querimonia.

The devolution of power was a reward for the Aranese pledging allegiance to James II in a dispute with the kingdoms of France and Majorca over control of the valley.

It was probably during his reign at Sicily (1285–1291) that James composed his only surviving piece of Occitan poetry, a religious dansa dedicated to the Virgin Mary, Mayre de Deu.

Mayre de Deu e fylha, verge humil e vera, vostra nau vos apela que l'aydetz, quar perylha.