In 1758-59, Caron became the harp tutor to King Louis XV's daughters. In 1759-60, Caron met Joseph Pâris-Duverney, an older and wealthy entrepreneur. The two became very close friends and collaborated on many business ventures. Shortly after his first marriage in 1756, Caron adopted the name "Pierre-Augustin Caron de Beaumarchais", which he derived from "le Bois Marchais", the name of a piece of land inherited by his first wife. Assisted by Pâris-Duverney, Beaumarchais acquired the title of secretary-councillor to the King in 1760-61, thereby gaining access to French nobility. This was followed by the purchase of a second title, the office of lieutenant general of hunting in 1763. The following year, Beaumarchais began a 10-month sojourn in Madrid, supposedly to help his sister, Lisette, who had been abandoned by her fiancé, Clavijo.

The passing of Pâris-Duverney in July 17, 1770 triggered a decade of turmoil for Beaumarchais. A few months before his death, the two signed a statement which cancelled all debts Beaumarchais owed Pâris-Duverney (about 75,000 pounds), and granting Beaumarchais the modest sum of 15,000 pounds. Pâris-Duverney's sole heir, Count de la Blache, took Beaumarchais to court, claiming the signed statement was a forgery. Although the 1772 verdict favoured Beaumarchais, it was overturned on appeal in the following year by a judge, magistrate Goezman, whose favour La Blache had managed to win over. At the same time, Beaumarchais was also involved in a dispute with Duke de Chaulnes over the Duke's mistress, which resulted in Beaumarchais's being thrown into jail from February to May, 1773. La Blache, took advantage of Beaumarchais's court absence and persuaded Goezman to order Beaumarchais to repay all his debts with Pâris-Duverney, plus interest and all legal expenses. To garner public support, Beaumarchais published a four-part pamphlet entitled Mémoires contre Goezman. The action made Beaumarchais an instant celebrity, for the public at the time perceived Beaumarchais as a champion for social justice and liberty. Goezman countered Beaumarchais's accusations by launching a law suit of his own. The verdict was equivocal. On February 26, 1774, both Beaumarchais and Mme. Goezman (who sympathised with Beaumarchais) were deprived of their civil rights, while Magistrate Goezman was removed from his post. To restore his civil rights, Beaumarchais pledged his services to Louis XV and Louis XVI. He travelled to London, Amsterdam and Vienna on various secret missions. His first mission was to travel to London to destroy a pamphlet, Les mémoires secrets d'une femme publique, that Louis XV considered a libel of one of his mistresses, Madame du Barry.

Beaumarchais was also remembered for his essential support for the American Revolution. Louis XVI, who did not want to break openly with England, allowed Beaumarchais to found a commercial enterprise, Roderigue Hortalez and Co., supported by the French and Spanish crowns, who supplied the American rebels with weapons, munitions, clothes, and provisions, which would never be paid for. Beaumarchais would deal with Silas Deane, an acting member of the Second Continental Congress's Committee of Secret Correspondence. For these services, the French Parliament reinstated his civil rights in 1776. Shortly after the death of Voltaire in 1778, Beaumarchais set out to publish Voltaire's complete works, many of which were banned in France.

It was not long before Beaumarchais crossed paths again with the French legal system. In 1787, he became acquainted with Mme. Korman, who was implicated and imprisoned in an adultery suit, which was filed by her husband to expropriate her dowry. The matter went to court, with Beaumarchais siding with Mme. Korman, and M. Korman assisted by a celebrity lawyer, Nicolas Bergasse. On April 2, 1790, M. Korman and Bergasse were found guilty of calumny (slander), but Beaumarchais's reputation was also tarnished.

Meanwhile, the French Revolution broke out. Beaumarchais was no longer the idol he had been a few years before. He was financially successful, mainly from supplying drinking water to Paris, and had acquired ranks in the French nobility. In 1791, he took up a lavish residence across from where the Bastille once stood. He spent under a week in prison during August 1792, and was released only three days before a massacre took place in the prison where he had been detained. Nevertheless, he pledged his services to the new Republic. He attempted to purchase 60,000 rifles for the French Revolutionary army from Holland, but was unable to complete the deal. While he was out of the country, Beaumarchais was declared an émigré (loyalists to the old regime) by his enemies. He spent two and a half years in exile, mostly in Germany, before his name was removed from the list of proscribed émigrés. He returned to Paris in 1796, where he lived out the remainder of his life in relative peace. He is buried in the Père Lachaise Cemetery in Paris.

Beaumarchais married three times. His first wife was Madeleine-Catherine Franquet (née Aubertin), whom he married on November 22, 1756, but died under mysterious circumstances only 10 months following the marriage. He later married Geneviève-Madeleine Lévêque (née Wattebled) in 1768. Again, the second Mme. de Beaumarchais died under mysterious circumstances two years later, though most scholars believed she actually suffered from tuberculosis. Beaumarchais had a son in 1770, Augustin, from his second marriage in 1770, but he also died in 1772. Beaumarchais lived with his lover, Marie-Thérèse de Willer-Mawlaz, for twelve years, before she became Beaumarchais's third wife, in 1786. Together they had a daughter, Eugénie. In his first two marriages, Beaumarchais was accused by his enemies of poisoning them in order to lay claim to their family inheritance. Beaumarchais, though having no shortage of lovers throughout his life, was known to be caring for both his family and close friends. However, Beaumarchais also had a reputation of marrying for financial gain, and both Franquet and Lévêque were previously married to wealthy families prior to Beaumarchais. While there was insufficient evidence to support the accusations, whether or not the poisonings took place is still subject of debate.