Pope Pious IX on 17 July 1851, by his Brief Maxima et præclarissima, recognised the Grand Master of the Constantinian Order, Ferdinand II King of the Two Sicilies. He also issued his Brief Quæ in rei sacræ on 17 September 1863, by which – due to the political changes in Italy in 1860 – he established that the Constantinian Church of Sant'Antonio Abate in Naples and all the Constantinian assets there kept would fall under the temporary rule of the Ordinary of Naples until the Holy See deemed this necessary.
Also Pope St. Pious X took care of the Order, by his Brief of 7 March 1910 in which he appointed Cardinal Domenico Ferrata as Protector of the Order, and by his Placet of 22 March 1911, by which he approved the elevation of the Abbey Church of Santa Maria a Cappella, also called Chiesa delle Crocelle, in Naples, as seat of the Order; and on 7 April 1911 and 2 April 1913, he gave his Placet to the magisterial decrees granting special insignia and other privileges to the Ecclesiastic Knights Chaplains of the Orders; on 3 December 1913 he appointed Cardinal Francesco di Paola Cassetta as new Protector of the Order.
In 1913 the Constantinian Order was a member of the Committee charged with the celebration of the XVI centennial celebration of the peace and freedom of the Church (Constantine Edict) and, by will of Pope St. Pious X, erected a chapel in the Church of the Holy Cross at Ponte Milvio, inaugurated on 22 May 1918 by a donation of the Ecclesiastic Knight Eugenio Pacelli, future Pope Pious XII; moreover, the Committee reconstructed the Constantinian labarum that would be blessed by Pope St. Pious X on 29 December 1913 in the Vatican before HRH the Duke of Calabria and now kept in the Seat of the Grand Chancellery of the Order in Naples.
Also Benedict XV showed benevolence to the Order: by his Brief Ad futuram rei memoriam of 13 December 1916, he made reference to a Brief of 17 September 1863 issued by his predecessor the Blessed Pious IX, and ruled the return of the Church of Sant'Antonio Abate to the Constantinian Order and recognised the then Grand Prior (and his successors) as Abbot of that Church with jurisdiction over the Constantinian Clergy for those things relevant to the Order; by his decree of 9 July 1919, he granted the Privilegium Officiorum to the clergy of the Sacred Military Constantinian Order, and approved the modifications made to the Statutes of the Order; then, by his Brief of 9 June 1919, he appointed Cardinal Vittorio Amedeo Ranuzzi de' Bianchi as Protector of the Order.

His Royal Highness Prince Ferdinand of Bourbon Two Sicilies Duke of Castro Head of the Royal House of Bourbon Two Sicilies Grand Master of the Dynastic Orders and Orders of Knighthood of the Royal House of the Bourbon of the Two Sicilies

Ettore Gallo authoritatively wrote: «From a general analysis and comparison of the above mentioned papal documents, the doctrine could make some important considerations: first of all the constant acknowledgement and gratitude of the Holy See towards the Constantinian Order; moreover, they show the assignment to its Grand Master – called many times as "perpetuus administrator Militiæ Auratæ Constantinianæ" in the papal documents - of the powers to appoint the Knights, to lead the Order and to interpret its ancient Farnese Statutes» .