MacDonald was born in Sedan, Ardennes, France. His father, Neil MacEachen, later MacDonald, came from a Jacobite family from Howbeg in South Uist, in the west of Scotland. He was a close relative of Flora MacDonald, who played a key role in the escape of Prince Charles Edward Stuart after the failure of the 1745 Rising.
In 1785, MacDonald joined the Irish legion raised to support the revolutionary party in the Dutch Republic against the Kingdom of Prussia. After it was disbanded, he received a commission in the regiment of Dillon. At the start of the French Revolution, the regiment of Dillon remained loyal to the King, except for MacDonald, who was in love with Mlle Jacob, whose father was an enthusiastic revolutionary. After his marriage, he was appointed aide-de-camp to General Charles François Dumouriez. He distinguished himself at the Battle of Jemappes, and was promoted colonel in 1793.
He refused to desert to the Austrians with Dumouriez, and as a reward was made general of brigade, and appointed to command the leading brigade in Pichegru's invasion of the Netherlands. His knowledge of the country proved useful, and he was instrumental in the capture of the Dutch fleet by French hussars. In 1797, having been made general of division, he served first in the army of the Rhine and later in that of Italy. When he reached Italy, the treaty of Campo Formio had been signed, and Bonaparte had returned to France; but, under the direction of Berthier, MacDonald occupied Rome, of which he was made governor, and then in conjunction with Championnet he defeated General Mack, and took the Kingdom of Naples, which became known as the Parthenopaean Republic.
When Suvorov invaded northern Italy, and was undoing the conquests of Bonaparte, MacDonald moved northwards. With 36,000 men he attacked Suvorov's 22,000 men at the Trebbia. After three days' fighting, receiving no help from Moreau, he was utterly defeated and fled to Genoa. Later he was made governor of Versailles, and acquiesced, even if he did not participate, in the events of the 18 Brumaire.
In 1800, he received command of the army in the Helvetic Republic, maintaining communications between the armies of Germany and of Italy. He carried out his orders diligently, and in the winter of 1800–01, he was ordered to march over the Splügen Pass at the head of the Army of the Grisons. This achievement is described by Mathieu Dumas, his chief of staff, and is as noteworthy as Bonaparte's passage of the St Bernard before the Battle of Marengo, although MacDonald did not fight a battle. On his return to Paris, MacDonald married the widow of General Joubert, and was appointed French ambassador to Denmark. Returning in 1805, he was associated with Moreau and thus incurred the dislike of Napoleon, who did not include him in his first creation of marshals.
He remained without employment until 1809, but then Napoleon made him military adviser to Prince Eugène de Beauharnais, viceroy of the Kingdom of Italy and a corps commander. He led the army from Italy to join with Napoleon, and at Wagram, led the attack which broke the Austrian centre and won the victory.
Napoleon made him a Marshal of France on the field of battle, and soon after created him duke of Taranto in the Kingdom of Naples.
In 1810, MacDonald served in Spain and in 1812, he commanded the left wing of the Grande Armée for the invasion of Russia. He was sent to the north but did not succeed in occupying Riga. In 1813, after participating in the battles of Lützen and Bautzen, he was ordered to invade Silesia, where Blücher defeated him with great loss at Katzbach. At the Battle of Nations in 1813, his force was pushed out at Liebertwolkwitz by Johann von Klenau's IV Corps (Austrian); on a counterattack, his troops took the village back. Later that day, Klenau foiled his attempt to flank the Austrian main army, commanded by Karl Philipp, Prince of Schwarzenberg. After the Battle of Leipzig, he was ordered to cover the evacuation of Leipzig with Prince Poniatowski. After the blowing up of the last bridge over the river, he managed to swim the Elster, but Poniatowski drowned. During the defensive campaign of 1814, MacDonald again distinguished himself. He was one of the marshals sent by Napoleon to take the notice of his abdication to Paris. When all were deserting Napoleon, MacDonald remained faithful. He was directed by Napoleon to give his adherence to the new régime, and was presented with the sabre of Murad Bey for his fidelity.
At the Restoration, he was made a peer of France and knight grand cross of the royal order of St. Louis; he remained faithful to the new order during the Hundred Days. In 1815, he became chancellor of the Legion of Honour, a post he held till 1831. In 1816, as major-general of the royal bodyguard, he took part in the debates of the Chamber of Peers, created under the Charter of 1814, voting consistently as a moderate Liberal.
From 1830, he lived in retirement at his country place Courcellesle-Roi (Seine-et-Oise), where he died on 25 September 1840(1840-09-25) (aged 74).
In 1791, he married Marie-Constance Soral de Montloisir (died 1797) and had 2 daughters:Anne-Charlotte (1792–1870)
In 1802, he married Felicite-Francoise de Montholon (died 1804), the widow of General Joubert, and had a daughter:Alexandrine-Aimee (1803–1869)
In 1821, he married Ernestine-Therese de Bourgoing (1789–1825) and had a son:Louis-Marie (1824–1881)
On 30 April 2010 a plaque was unveiled to the memory of Marshal of France Jacques MacDonald on the Outer Hebridean island of South Uist, the familial home of MacDonald. MacDonald had visited South Uist in 1825 in order to find out more about his family roots.
Of him, the Encyclopædia Britannica of 1911 says:
MacDonald had none of that military genius that distinguished Davout, Masséna and Lannes, nor of that military science conspicuous in Marmont and St Cyr, but nevertheless his campaign in Switzerland gives him a rank far superior to such mere generals of division as Oudinot and Dupont. This capacity for independent command made Napoleon, in spite of his defeats at the Trebia and the Battle of Katzbach, trust him with large commands till the end of his career. As a man, his character cannot be spoken of too highly; no stain of cruelty or faithlessness rests on him.