Upon Cardinal Mazarin's return, Fouquet demanded and received as reward the office of superintendent of the finances (1653), a position which, in the unsettled condition of the government, threw into his hands not merely the decision as to which funds should be applied to meet the demands of the state's creditors, but also the negotiations with the great financiers who lent money to the king. The appointment was a popular one with the moneyed class, for Fouquet's great wealth had been largely augmented by his marriage in 1651 with Marie de Castille, who also belonged to a wealthy family of the legal nobility.
His own credit, and above all his unfailing confidence in himself, strengthened the credit of the government, while his high position at the parlement (he still remained procureur général) secured financial transactions from investigation. As minister of finance, he soon had Mazarin almost in the position of a suppliant. The long wars, and the greed of the courtiers, who followed the example of Mazarin, made it necessary at times for Fouquet to meet the demands upon him by borrowing upon his own credit, but he soon turned this confusion of the public purse with his own to good account.
The disorder in the accounts became hopeless; fraudulent operations were entered into with impunity, and the financiers were kept in the position of clients by official favours and by generous aid whenever they needed it. Fouquet's fortune now surpassed even Mazarin's, but the latter was too deeply implicated in similar operations to interfere, and was obliged to leave the day of reckoning to his agent and successor Jean-Baptiste Colbert.
Upon Mazarin's death Fouquet expected to be made head of the government; but Louis XIV was suspicious of his poorly dissembled ambition, and it was with Fouquet in mind that he made the well-known statement, upon assuming the government, that he would be his own chief minister. Colbert fed the king's displeasure with adverse reports upon the deficit, and made the worst of the case against Fouquet. The extravagant expenditure and personal display of the superintendent served to intensify the ill-will of the king. Fouquet had bought the port of Belle-Isle and strengthened the fortifications, with a view to taking refuge there in case of disgrace.
He had spent enormous sums in building a magnificent château on his estate of Vaux-le-Vicomte, which in extent, magnificence, and splendour of decoration was a forecast of Versailles, and where he brought together three artists that the king would take up for Versailles: the architect Louis Le Vau, the painter Charles Le Brun, and the garden designer André le Nôtre. Here he gathered the rarest manuscripts, the finest paintings, jewels and antiques in profusion, and above all surrounded himself with artists and authors. The table was open to all people of quality, and the kitchen was presided over by François Vatel. Jean de La Fontaine, Corneille, and Paul Scarron were a few of the many artists who enjoyed his patronage.
In August 1661 Louis XIV, already set upon his destruction (his disgrace was secretly decided upon on May 4), was entertained at Vaux with a fête rivalled in magnificence by only one or two in French history, at which Molière's Les Fâcheux was produced for the first time. The splendour of the entertainment sealed Fouquet's fate. The king, however, was afraid to act openly against so powerful a minister. By crafty devices Fouquet was induced to sell his office of procureur general, thus losing the protection of its privileges, and he paid the price of it into the treasury.
Three weeks after his visit to Vaux the king withdrew to Nantes, taking Fouquet with him. When he was leaving the presence chamber, flattered with the assurance of his esteem, Fouquet was arrested by a captain of musketeers named d'Artagnan. The trial lasted almost three years, and its violation of the forms of justice is still the subject of frequent monographs by members of the French bar. Public sympathy was strongly with Fouquet, and La Fontaine, Madame de Sévigné and many others wrote on his behalf; but when Fouquet was sentenced to banishment, the king, disappointed, commuted the sentence to imprisonment for life. He was sent at the beginning of 1665 to the fortress of Pignerol, where, according to official records, he died on March 23, 1680.
Louis acted throughout "as though he were conducting a campaign," evidently fearing that Fouquet would play the part of a Richelieu. Fouquet bore himself with manly fortitude, and composed several mediocre translations in prison. The devotional works bearing his name are apocryphal. A report of his trial was published in the Netherlands, in 15 volumes, in 1665—1667, in spite of the remonstrances which Colbert addressed to the States-General. A second edition under the title of Oeuvres de M. Fouquet appeared in 1696.
Some have suggested that Fouquet was the famous Man in the Iron Mask, but this theory is quite implausible since letters sent between the jail and ministers in Paris indicate that Eustache Dauger, the man identified as the masked prisoner, served as Fouquet's manservant at Pignerol prison.
Fouquet is a pivotal character in Alexandre Dumas' novel The Vicomte de Bragelonne, where he is depicted sympathetically. Aramis, an ally of Fouquet, tries to seize power by replacing Louis XIV with his identical twin brother. It is Fouquet who, out of sheer loyalty for the crown, foils Aramis' plot and saves Louis. This does not, however, prevent his downfall.
James Whale's film The Man in the Iron Mask is very loosely adapted from Dumas' novel and, on the contrary, depicts Fouquet as the story's main villain, who tries to keep the existence of the King's twin brother a secret. Fouquet is portrayed by Joseph Schildkraut. In a departure from history, he dies when his coach plunges off a cliff. In the 1977 version, Fouquet is portrayed by Patrick McGoohan.
He was also portrayed by Robert Lindsay in Nick Dear's play "Power". This debuted at the national theatre in 2003.