Poinsett was a strong supporter of Andrew Jackson during the early to mid-19th century in favor of his policies of Jacksonian democracy.

He was Unionist leader in South Carolina during that state's threatened refusal to accept and enforce certain federal laws and tariff levies on imported goods in the earlier secessionist rebellion of the Nullification Crisis of the 1830s.

Poinsett was compelled to assume the role of interpreter between the deaf Livingston and the aged Necker, whose lack of teeth made his speech almost incomprehensible.

As the sole remaining heir, Poinsett inherited a small fortune in town houses and lots, plantations, bank stock, and "English funds."

Levett Harris, consul of the United States at St. Petersburg, and the highest American official in the country, hoped to introduce Poinsett at court to Czar Alexander.

Poinsett did not believe the cotton industry could be successful in Russia because of the necessity of employing serfs who received no compensation and therefore could have no interest in its prosperity.

This new security increased the numbers in Poinsett's company, which they believed made it less vulnerable to attack as it passed out of Russia proper.

Thus, they were joined by a Persian merchant, who was transporting young girls he had acquired in Circassia to Baku, Azerbaijan and harems in Turkey.

The Khan was impressed and told Poinsett that the head of the guilty chief was his for the asking, yet since the thief had made it possible for him to accept such a distinguished visitor, perhaps a pardon might be in order.

He became one of the earliest U.S. travelers to the Middle East, where, in 1806, the Persian khan showed him a pool of petroleum, which he speculated might someday be used for fuel.

Avoiding Constantinople because of conflict between Russia and the Ottoman Empire, the party proceeded to the Crimea, then through Ukraine, reaching Moscow late in 1807.

Upon his return to Moscow, Czar Alexander discussed the details of Poinsett's trip with him and offered him a position as colonel in the Russian Army.

The Tribunal del Consulado, the organization with jurisdiction over commercial matters opposed his reception on the grounds that his nomination had not been confirmed by the U.S. Senate.

He declared the laws of the new Chilean government relative to free commerce null and void and sent privateers to enforce the old colonial system.

Poinsett learned of the seizure of an American whaler searching for supplies from an intercepted letter from the governor of San Carlos de Chiloe to the viceroy of Lima.

After a consultation with Carrera, Poinsett accepted a commission into the Chilean army to fight against the Spanish Royalists based in Peru.

In early September 1813, the United States Frigate Essex arrived in Chilean waters, forcibly seizing the British whalers in the area.

After waiting six weeks, Porter decided to launch a desperate breakout but was easily defeated by Captain James Hillyar of the Phoebe.

He managed to negotiate a commercial agreement with the Junta by which American articles of general consumption were admitted free of duty.

Poinsett wrote Carrera back stating that he intended to urge the U.S. government to develop decisive policy regarding the Spanish colonies.

On August 29, 1816, Poinsett, along with four free men and one enslaved man from Charleston, set out from Philadelphia on a tour of the western United States.

In May, Poinsett explained to President James Monroe that he had recently accepted a seat in the legislature of South Carolina and could not resign it "without some more important motive than this commission presents."

In December 1823, Poinsett submitted a resolution calling upon the Committee on Naval Affairs to inquire into the expediency of authorizing the construction of ten additional sloops of war.

[5] (Poinsett wrote Notes on Mexico, a memoir of his time in the First Mexican Empire and at the court of Agustín de Iturbide.

)[4] [6] He became embroiled in the country's political turmoil until his recall in 1830, but he did try to further U.S. interests in Mexico by seeking preferential treatment of U.S. goods over those of Britain, attempting to shift the U.S.–Mexico boundary, and urging the adoption of a constitution patterned on that of the U.S.[4] After visiting an area south of Mexico City near Taxco de Alarcón, Poinsett saw what later became known in the United States as the poinsettia.

Poinsett served as Secretary of War from March 7, 1837, to March 5, 1841, overseeing the Trail of Tears, and presided over the continuing suppression of Native American raids by removal of Indians west of the Mississippi and over the Seminole War; reduced the fragmentation of the army by concentrating elements at central locations; equipped the light batteries of artillery regiments as authorized by the 1821 army organization act; and again retired to his plantation at Georgetown, South Carolina, in 1841.

During the 1820s, Poinsett was a member of the prestigious society, the Columbian Institute for the Promotion of Arts and Sciences, who counted among their members former presidents Andrew Jackson and John Quincy Adams and many prominent men of the day, including well-known representatives of the military, government service, medical and other professions.

[15] Poinsett played a prominent role in defining Freemasonry in Mexico; he favoured promoting the York Rite, which was allied to the political interests of the United States.

He died of tuberculosis, hastened by an attack of pneumonia, in Stateburg, South Carolina, in 1851, and is buried at the Church of the Holy Cross Episcopal Cemetery.

Lindsay Schakenbach Regele, Flowers, Guns, and Money: Joel Roberts Poinsett and the Paradoxes of American Patriotism (The University of Chicago Press, 2023).