This portrait of Sebastián I of Portugal may be a reduced version of a full-length portrait in the Monasterio de las Descalzas Reales, Madrid signed by the artist Cristóvão de Morais, who was active at the Royal court in Lisbon between 1551 and 1573. Morais painted a number of portraits of the young King Sebastian which were sent to his mother, Joanna of Austria, who had been forced to leave her only son behind when she travelled to Spain to rule as regent.

Sebastian I was the only son of John Manuel of Portugal and his wife Joanna of Austria. His father died two weeks before his birth in January 1554 and in 1557 at the age of only three, Sebastian succeeded his grandfather John III to the Portuguese throne. Sebastian I was devoutly religious and dedicated his reign to reinstating the costly crusades abandoned by John III. In 1578, Sebastian led a large force to Larache, where they were defeated by a superior Moroccan army. Following Sebastian I's disappearance during the crusade, a myth developed that the King had survived the battle and would return to free Portugal of Spanish rule.

Little is known of the early life of painter Cristóvão de Morais. He is believed to have been apprenticed to the workshop of Dutch painter Cornelis Buys II in Antwerp and was active at the Portuguese court by 1551, serving first John III and later his grandson Sebastian I. In 1554, he was appointed Examiner of Painters. A disciple of Spanish court painter Alonso Sanchez Coello, his style followed the conventions of Habsburg portraiture of the sixteenth century. Like Coelle, Morais's portraiture combines the Venetian influence of Titian with a Flemish attention to detail that shows the impact of Anthonis Mor van Dashorst, who was present at the Portuguese court in 1552 before becoming court painter to Philip II of Spain.

This head and shoulders portrait of Sebastián I shows the young King in court dress, wearing a small, high ruff, a jewelled cap with feather, two gold chains and a cloak over his doublet, which is embroidered with alternating bands of gold. Like other portraits of Habsburg kings of this period, the painting represents Sebastian I as the embodiment of power, authority and the Christian virtues associated with a King as defender of the Catholic faith.