Born in Palermo, Sicily, Italy on April 27, 1806, she was the daughter of King Francis I (In Italian, Francesco I) of the Two Sicilies by his second wife, Infanta Doña Maria Isabel of Spain. She married King Ferdinand VII of Spain on December 11, 1829 in Madrid. Ferdinand was her uncle by birth and by marriage. Like her mother Maria Isabel, Ferdinand was a child of King Charles IV of Spain (Carlos IV in Spanish) and his wife, Princess Maria Luisa of Bourbon-Parma. Further, Ferdinand's first wife Princess Maria Antonietta of Naples and Sicily (1784-1806) was the sister of Maria Christina's father, King Francis. After Maria Antonietta's death, Ferdinand married Infanta Doña Isabel of Portugal (1787-1819). When Isabel died he married Princess Josepha of Saxony (1803-1829). Of these three marriages, only that to Isabel resulted in a live child. Queen Isabel's daugther, the Infanta Doña María Luísa Isabel, died on January 9, 1818 at the age of four months. With Queen Josepha's death on May 27, 1829, Ferdinand's was desperation to father an heir for his crown resulted in his fourth marriage just seven months later.
The new queen, Maria Christina, rapidly gave birth to two daughters, Isabella (the future Queen Isabella and the Infanta Doña María Luísa Fernanda (1832-1897). When Ferdinand died on September 29, 1833, Maria Christina became regent for their daughter Isabella. Isabella's claim to the thrown was disputed by her uncle, the Infante Don Carlos María Isidro Benito, Count de Molina, who claimed that Ferdinand had unlawfully changed the succession law to permit females to inherit the crown. Some supporters of Carlos went so far as to claim that Ferdinand had actually bequeathed the crown to his brother but that Maria Christina had suppressed that fact. It was further alleged that the Queen had signed her dead husband's name to a decree recognizing Isabella as heir.
Carlos' attempt to seize power resulted in the Carlist Wars. Despite considerable support for Carlos from the Roman Catholic Church and conservative elements in Spain, Maria Christina successfully retained the throne for her daughter. The Carlist Wars grew from a dispute about the succession into a dispute over the future of Spain. The supporters of Maria Christina and her daughter favored a liberal constitution and progressive social policies. In contrast, Carlos' supporters (called Carlists) favored a return to traditional society and an absolute monarchy. Ultimately, the army's loyalty to Isabella II proved the decisive issue in the war.
On December 28, 1833, shortly after the death of Ferdinand VII, Maria Christina secretly married an ex-sergeant from the royal guard, Don Fernando Muñoz y Sanchez (1808 to 1873). Muñoz was given the title Duke of Riansares. Maria Christina and Muñoz had several children together while trying to keep their marriage a secret. Eventually, news of Maria Christina's marriage to low-ranking soldier became public. That news made Maria Christina deeply unpopular.
The Regent's position was undermined by news of her remarriage and concerns that Maria Christina was not actually supportive her liberal ministers and their policies. Eventually, the army, which was the backbone of Isabella II's support, and the liberal leadership in the Cortes combined to demand that Maria Christina stand aside from the regency. In 1840, the army commander, General Baldomero Esparto, replaced her as regent.
The new government required the ex-regent to leave Spain. After an unsuccessful attempt to return to power, Maria Christina retired permanently to exile in France after 1844. France remained her primary residence for the remainder of her life. A Revolution forced Isabella II from her throne on September 30, 1868 and she joined her mother in exile in France.
Isabella II renounced the throne in favor of her son, Alfonso XII on June 25th, 1870. Supporters of Alfonso XII made it clear that neither his mother nor grandmother could play an active role in the effort to restore the monarchy. When Alfonso XII regained the Spanish crown on December 29th, 1874, Maria Christina and Isabella II were permitted to return to Spain as visitors but denied permission to live there permanently. Neither was allowed to exercise influence in the Spanish government.
The marriage to Muñoz and the events of Maria Christina's turbulent regency drove a permanent wedge between her and her Spanish Royal offspring. Neither Isabella II nor Alphonso XII had much interest in a relationship with the former Queen Regent. Maria Christina died in Le Havre, France on August 22nd, 1878. As the widow of Ferdinand VII and the mother of Isabella II, Maria Christina was buried in the royal crypt of the El Escorial monastery (El Real Monasterio de San Lorenzo del Escorial, The Royal Moneastery of Saint Lawrence of Escorial). Burial in the royal crypt is a privilege reserved to Spanish sovereigns and such of their spouses who were actually the parents of future sovereigns. Ferdinand VII's first three wives had to be buried in less exalted parts of the Escorial or other churches.