He was born in Cannes, France, the ninth child but fifth son of Prince Alfonso, Count of Caserta and Princess Maria Antonietta of Bourbon-Two Sicilies (1851–1938). Ranieri for a time served in the Royal Spanish Army.

Following the death of his brother Prince Ferdinand Pius, Duke of Calabria on 7 January 1960 Prince Ranieri was declared Head of the House of Bourbon-Two Sicilies by all relatives except for Infante Alfonso, Duke of Calabria and his children, because the Infante's senior branch of the family abdicated their claims in order to be in line for the Spanish throne.^[1] He remained head of the house until his death on 13 January 1973 in Lacombe. He handed over the functions associated with the headship of the house to his son in 1966.^[2]

Ranieri married his first cousin Countess Maria Carolina Zamoyska (1896–1968) on 12 September 1923 in Vyšné Ružbachy, Slovakia, from the marriage he had two children:

• Princess Maria del Carmen Carolina Antonia of Bourbon-Two Sicilies (1924–2018).
• Prince Ferdinando Maria Andrea Alfonso Marcus, Duke of Castro (1926–2008).

• Grand Master of the Sacred Military Constantinian Order of Saint George
• Grand Master of the Order of Saint Januarius
• Grand Master of the Order of Saint Ferdinand and of Merit
• Grand Master of the Royal Order of Francis I
• Grand Master of the Order of Saint George and Reunion
• Knight of the Spanish Order of the Golden Fleece
• Knight of the Order of Saint Hubert of Bavaria
• Knight of the Supreme Order of the Most Holy Annunciation
• Bailiff Grand Cross of Honor and Devotion of the Sovereign Military Order of Malta
• Knight Grand Cross of the Order of Charles III
• Knight of the Order of Alcántara

• Heraldry of Prince Ranieri
•  
  Prince Rainieri's arms
  Until 1960
•  
  Prince Rainieri's arms
  used in Spain
•  
  Prince Ranieri's arms as head of the Royal House
  1960-1973

• Royal House of Bourbon-Two Sicilies