The oldest known document relating to the Constantinian Knights dates back to 1190 and is the statute reformed by the Eastern Emperor Isaac IV Angelus Flavius Comnenus. The Grand Magistery passed from father to son in the Comnenus dynasty until the last of them, who, to avoid its extinction for lack of successors, transferred it to the Duke of Parma, Francesco Farnese. The transfer was sanctioned by the bull “Sincerae fidei” of October 24, 1697, by Pope Innocent XII. Pope Clement XI, formerly Cardinal Protector of the Order, with the bull “Militantis Ecclesiae” of May 27, 1718, placed the Order under the protection of the Holy See and granted abbatial privileges to the Grand Prior. Antonio Farnese, the last Duke of Parma, transferred the supreme dignity of the Order to Charles of Bourbon, son of his niece Elisabeth Farnese and Philip V, King of Spain, who, upon ascending the throne of Naples, established the seat of the Order there and, in 1759, transferred his rights to his son Ferdinand IV. He was succeeded by Francis I (1825-1830), Ferdinand II (1830-1859), and Francis II (1836-1894), the last King of the Two Sicilies.

Italian unification deprived the Constantinian Order of its material assets, but the Royal House of Bourbon of the Two Sicilies retained the Grand Magistery as it constitutes a dynastic family Order.

The current Grand Master is H.R.H. Prince Charles of Bourbon-Two Sicilies, Duke of Castro and Head of the Royal House. He succeeds his father H.R.H. Prince Ferdinand (who died on March 20, 2008), who in turn succeeded Prince Ranieri, who had taken over the title from his brother, Prince Ferdinand Pius; both of the latter were sons of Prince Alfonso, Count of Caserta, who was in turn the brother of H.M. Francis II, the last Sovereign of the House of Bourbon of the Two Sicilies who reigned over Southern Italy until 1861.
The Grand Master governs the Order assisted by the Royal Deputation, composed of the Great Offices: Grand Prefect, Grand Prior, Grand Chancellor, and Grand Treasurer; by the President, Vice President, and Secretary, and by the deputies, appointed for a three-year term. H.R.H. the Grand Master is also assisted by a Magisterial Legal Council and, for the heraldic and noble part, by a Magisterial Heraldic Commission. Knights and Dames are divided into three categories: Justice, Grace, and Merit.

The Italian State has formally recognized the legitimacy of the Order and, since 1963, has authorized Italian citizens to wear its decorations pursuant to Art. 7 of Law 178 of March 3, 1951. The Order is also registered with the Chancellery of the Court of Naples in the register of legal entities.
Italian citizens awarded the Cross of the Order may join the National Association of Italian Constantinian Knights (A.N.C.C.I.), established as a non-profit entity by Decree of the President of the Republic on March 30, 1973.

Since August 1, 2011, the Constantinian Order has enjoyed special consultative status with the Economic and Social Council of the United Nations (ECOSOC-UN).

The Order has delegations in all regions of Italy, in Europe, and is represented in numerous other states around the world.