The Constantinian Order enjoys an excellent relationship with the Sovereign Military Order of Malta and this dates back to the time when the Kingdom of the Two Sicilies historically enjoyed a close relationship with the island of Malta, with which it maintained a treaty granting military protection. Since 1878, every Prince and Grand Master of the Order of Malta has been a senior member of the Constantinian Order.
His Eminent Highness Prince Fra’ Giacomo Dalla Torre del Tempio di Sanguinetto was the 80th Grand Master of the Sovereign Military Order of Malta from May 2nd 2018 until April 29th 2020.
His Royal Highness Prince Charles of Bourbon Two Sicilies, Duke of Castro, as Head of the Royal House and Grand Master of the Dynastic Orders, appointed him as Baillif Knight Grand Cross of Justice in May 1995 and on the occasion of his election as Grand Master of the Order of Malta, Fra’ Giacomo Dalla Torre del Tempio di Sanguinetto was granted the Royal Order of Saint Januarius and the Constantinian Collar.
Meeting between His Eminent Highness Prince Fra’ Giacomo Dalla Torre del Tempio di Sanguinetto and His Royal Highness Prince Charles of Bourbon Two Sicilies
Meeting between His Eminent Highness Prince Fra’ Giacomo Dalla Torre del Tempio di Sanguinetto and His Royal Highness Prince Charles of Bourbon Two Sicilies
His Most Eminent Highness Fra’ Matthew Festing 79th Grand Master received in private audience by Pope Benedict XVI
The 79th Prince and Grand Master, His Most Eminent Highness Frà Matthew Festing has had a long association with the Sacred Military Constantinian Order of Saint George. Frà Festing served on the Council of the British and Irish Delegation of the Constantinian Order from 2002-2009 having been first invested as a Knight of Justice of the Constantinian Order of Saint George in 1991.
In 1994 the Grand Master of the Constantinian Order promoted Frà Matthew Festing to the grade of Knight Grand Cross of Justice. In 2010 the Grand Master further honoured him through his appointment as a Knight of the Royal Order of Saint Januarius and to Bailiff Grand Cross with Collar decoration of the Constantinian Order.
Until his death in 2008, the 78th Prince and Grand Master, H.M.E.H. Frà Andrew Bertie, was also a longstanding knight having been invested by H.R.H. The Duke of Castro into the Sacred Military Constantinian Order in 1985 as a Knight Grand Cross of Justice of the Order. Frà Bertie was later elevated to the rank of Bailiff Grand Cross with Collar in 1988 – the highest distinction within the Sacred 
Military Constantinian Order of St. George and in 1993 was invested as a Knight of Royal Order of Saint Januarius – the most senior Order of the Royal House of Bourbon Two Sicilies.
H.R.H. Prince Ferdinand, Duke of Castro, the Constantinian Order’s Grand Master until his death in March 2008 was invested as a Bailiff Grand Cross of Honour and Devotion of the Order of Malta in December 1968. In 1988, the late Duke of Castro, also received from Frà Andrew Bertie, Prince and Grand Master, the rare award of an Honorary Cross of Profession. HRH Princess Chantal, Duchess of Castro, was promoted within the Order of Malta to the rank of Dame Grand Cross of Honour and Devotion in 1996.
H.R.H. Prince Charles, Duke of Castro, who first entered the Sovereign Military Order of Malta in May 1983, was promoted in February 2004 to the grade of Bailiff Grand Cross of Honour and Devotion.
78th Prince and Grand Master, His Most Eminent Highness Frà Andrew Bertie
H.R.H. Princess Camilla, Duchess of Castro was invested as a Dame Grand Cross of Honour and Devotion in October 2001.
Many senior officers of the Order of Malta across the world are members of the Constantinian Order and some hold official positions within the Grand Magistry of the Constantinian Order.