The Chapel of the Langue of Aragon, including the priories of Catalunia and Navarre, is dedicated to St George. It is one of the most richly embellished chapels in the church. The altar painting within this chapel represents St George on Horseback and was executed by Mattia Preti as one of his first works for the church which was commissioned by Grand Master Martin de Redin in 1659. Also executed by Preti within this chapel are the lateral paintings representing St Francis Xavier and St Firminius and the paintings within the lunettes depicting St Lawrence meeting Pope Sixtus II on his way to Martyrdom and The Martyrdom of St Lawrence. The altar and its surrounds were redesigned in the 18th century during the reign of Grand Master Ramon Despuig. His effigy is displayed at the base of the marble columns.
There are four Grand Masters buried in this chapel. The funerary monuments close to the altar are of Grand Master de Redin who reigned from 1657 to 1660 and of Grand Master Raphael Cotoner who reigned from 1660 to 1663. Grand Master Raphael was superseded by his brother Nicholas whose monument is also present within the chapel. The other monument is that of Grand Master Perellos Y Roccaful who reigned from 1697-1720.
The chapel was bestowed with several important relics brought to Malta by the knights. Amongst them are the arm of St George, the arm of St Vincent Ferreri, a relic of the true cross and the entire body of St Fidele, martyr, which is kept in the altar of the Chapel.