structural:expansion, quality:correction, structural:reformatting
Later reign (1320–1329)

The reign of Robert Bruce also included some significant diplomatic achievements. The Declaration of Arbroath of 1320 strengthened his position, particularly in relation to the Papacy, and Pope John XXII eventually lifted Bruce's excommunication. In May 1328 King Edward III of England signed the Treaty of Edinburgh–Northampton, which recognised Scotland as an independent kingdom, and Bruce as its king.

In 1325 Robert I acquired lands at Cardross in exchange for those of Old Montros in Angus, Scotland, with Sir David Graham. It was to be here in Cardoss that Robert would build the manor house that would serve as his favoured residence during the final years of his reign. The extant chamberlain's accounts for 1328 detail a manor house at Cardross with king's and queen's chambers and glazed windows, a chapel, kitchens, bake- and brew-houses, falcon aviary, medicinal garden, gatehouse, protective moat and a hunting park. There was also a jetty and beaching area for the 'king's coble' (for fishing) alongside the "king's great ship". As most of mainland Scotland's major royal castles had remained in their razed state since around 1313–1314, Cardross manor was perhaps built as a modest residence sympathetic to Robert's subjects' privations through a long war, repeated famines and livestock pandemics. Before Cardross became habitable in 1327, Robert's main residence had been Scone Abbey.

Robert had been suffering from a serious illness from at least 1327. The Lanercost Chronicle and Scalacronica state that the king was said to have contracted and died of leprosy. Jean Le Bel also stated that in 1327 the king was a victim of 'la grosse maladie', which is usually taken to mean leprosy. However, the ignorant use of the term 'leprosy' by fourteenth-century writers meant that almost any major skin disease might be called leprosy. The earliest mention of this illness is to be found in an original letter written by an eyewitness in Ulster at the time the king made a truce with Sir Henry Mandeville on 12 July 1327. The writer of this letter reported that Robert was so feeble and struck down by illness that he would not live, 'for he can scarcely move anything but his tongue'. However, none of the several accounts of his last years by people who were with him refer to any sign of a skin ailment. Barbour writes of the king's illness that "it began through a benumbing brought on by his cold lying", during the months of wandering from 1306 to 1309. It has been proposed alternatively that he had eczema, tuberculosis, syphilis, motor neuron disease, cancer or a series of strokes. There does not seem to be any evidence as to what the king himself or his physicians believed his illness to be. Nor is there any evidence of an attempt in his last years to segregate the king in any way from the company of friends, family, courtiers, or foreign diplomats.

In October 1328 the Pope finally lifted the interdict from Scotland and the excommunication of Robert. The king's last journey appears to have been a pilgrimage to the shrine of Saint Ninian at Whithorn; this was possibly in search of a miraculous cure, or to make his peace with God. With Moray by his side, Robert set off from his manor at Cardross for Tarbert on his 'great ship', thence to the Isle of Arran, where he celebrated Christmas of 1328 at the hall of Glenkill near Lamlash. Thence he sailed to the mainland to visit his son and his bride, both mere children, now installed at Turnberry Castle, the head of the earldom of Carrick and once his own main residence. He journeyed overland, being carried on a litter, to Inch in Wigtownshire: houses were built there, and supplies brought to that place, as though the king's condition had deteriorated. At the end of March 1329, he was staying at Glenluce Abbey and at Monreith, from where St Ninian's Cave was visited. Early in April, he arrived at the shrine of St Ninian at Whithorn. He fasted four or five days and prayed to the saint, before returning by sea to Cardross.

Barbour and other sources relate that Robert summoned his prelates and barons to his bedside for a final council at which he made copious gifts to religious houses, dispensed silver to religious foundations of various orders, so that they might pray for his soul, and repented of his failure to fulfil a vow to undertake a crusade to fight the ' Saracens ' in the Holy Land. Robert's final wish reflected conventional piety, and was perhaps intended to perpetuate his memory. After his death his heart was to be removed from his body and, accompanied by a company of knights led by Sir James Douglas, taken on pilgrimage to the Church of the Holy Sepulchre in Jerusalem before being interred in Melrose Abbey upon its return from the Holy Land:

I will that as soone as I am trespassed out of this worlde that ye take my harte owte of my body, and embawme it, and take of my treasoure as ye shall thynke sufficient for that enterprise, both for your selfe and suche company as ye wyll take with you, and present my hart to the holy Sepulchre where as our Lorde laye, seyng my body can nat come there.

Robert also arranged for perpetual soul masses to be funded at the chapel of Saint Serf, at Ayr and at the Dominican friary in Berwick, as well as at Dunfermline Abbey.