The Macartney Embassy (Chinese: 馬加爾尼使團), also called the Macartney Mission, was the first British diplomatic mission to China, which took place in 1793. It is named for its leader, George Macartney, Great Britain's first envoy to China. The goals of the mission included the opening of new ports for British trade in China, the establishment of a permanent embassy in Beijing, the cession of a small island for British use along China's coast, and the relaxation of trade restrictions on British merchants in Guangzhou (Canton). Macartney's delegation met with the Qianlong Emperor, who rejected all of the mission's requests. Although the mission failed to achieve its official objectives, it was later noted for the extensive cultural, political, and geographical observations its participants recorded in China and brought back to Europe. It came to light in 1796 that a Chinese court official, Heshen, was embezzling state funds and had frustrated the mission.

Foreign maritime trade in China was regulated through the Canton System, which emerged gradually through a series of imperial edicts in the 17th and 18th centuries. This system channeled formal trade through the Cohong, a guild of thirteen trading companies (known in Cantonese as "hong") selected by the imperial government. In 1725, the Yongzheng Emperor gave the Cohong legal responsibility over commerce in Guangzhou. By the 18th century, Guangzhou, known as Canton to British merchants at the time, had become the most active port in the China trade, thanks partly to its convenient access to the Pearl River Delta. In 1757, the Qianlong Emperor confined all foreign maritime trade to Guangzhou. Qianlong, who ruled the Qing dynasty at its zenith, was wary of the transformations of Chinese society that might result from unrestricted foreign access. Chinese subjects were not permitted to teach the Chinese language to foreigners, and European traders were forbidden to bring women into China.

By the late 18th century, British traders felt confined by the Canton System and, in an attempt to gain greater trade rights, they lobbied for an embassy to go before the emperor and request changes to the current arrangements. The need for an embassy was partly due to the growing trade imbalance between China and Great Britain, driven largely by the British demand for tea, as well as other Chinese products like porcelain and silk. The East India Company, whose trade monopoly in the East encompassed the tea trade, was obliged by the Qing government to pay for Chinese tea with silver. To address the trade deficit, efforts were made to find British products that could be sold to the Chinese.

At the time of Macartney's mission to China, the East India Company was beginning to grow opium in India to sell in China. The company made a concerted effort starting in the 1780s to finance the tea trade with opium. Macartney, who had served in India as Governor of Madras (present-day Chennai), was ambivalent about selling the drug to the Chinese, preferring to substitute "rice or any better production in its place". An official embassy would provide an opportunity to introduce new British products to the Chinese market, which the East India Company had been criticised for failing to do.

In 1787, Prime Minister William Pitt the Younger and East India Company official Henry Dundas dispatched Colonel Charles Cathcart to serve as Britain's first ambassador to China. Cathcart became ill during the voyage, however, and died just before his ship, HMS Vestal, reached China. After the failure of the Cathcart Embassy, Macartney proposed that another attempt be made under his friend Sir George Staunton. Dundas, who had become Home Secretary, suggested in 1791 that Macartney himself take up the mission instead. Macartney accepted on the condition that he would be made an earl, and given the authority to choose his companions.

Macartney chose George Staunton as his right-hand man, whom he entrusted to continue the mission should Macartney himself prove unable to do so. Staunton brought along his son, Thomas, who served the mission as a page. John Barrow (later Sir John Barrow, 1st Baronet) served as the embassy's comptroller. Joining the mission were two doctors (Hugh Gillan and William Scott), two secretaries, three attachés, and a military escort. Artists William Alexander and Thomas Hickey would produce drawings and paintings of the mission's events. A group of scientists also accompanied the embassy, led by James Dinwiddie.

It was difficult for Macartney to find anyone in Britain who could speak Chinese because it was illegal for Chinese people to teach foreigners. Chinese who taught foreigners their language risked death, as was the case with the teacher of James Flint, a merchant who broke protocol by complaining directly to Qianlong about corrupt officials in Canton. Macartney did not want to rely on native interpreters, as was the custom in Canton. The mission brought along four Chinese Catholic priests as interpreters. Two were from the Collegium Sinicum in Naples, where George Staunton had recruited them: Paolo Cho (周保羅) and Jacobus Li (李雅各; 李自標; Li Zibiao). They were familiar with Latin, but not English. The other two were priests at the Pontificio Collegio Urbano de Propaganda Fide, which trained Chinese boys brought home by missionaries in Christianity. The two wanted to return home to China, to whom Staunton offered free passage to Macau. The 100-member delegation also included scholars and valets.

Among those who had called for a mission to China was Sir Joseph Banks, 1st Baronet, President of the Royal Society. Banks had been the botanist on board HMS Endeavour for the first voyage of Captain James Cook, as well as the driving force behind the 1787 expedition of HMS Bounty to Tahiti. Banks, who had been growing tea plants privately since 1780, had ambitions to gather valuable plants from all over the world to be studied at the Royal Botanic Gardens at Kew and the newly established Calcutta Botanical Garden in Bengal. Above all, he wanted to grow tea in Bengal or Assam, and address the "immense debt of silver" caused by the tea trade. At this time, botanists were not yet aware that a variety of the tea plant (camellia sinensis var. assamica) was already growing natively in Assam, a fact that Robert Bruce was to discover in 1823. Banks advised the embassy to gather as many plants as possible in their travels, especially tea plants. He also insisted that gardeners and artists be present on the expedition to make observations and illustrations of local flora. Accordingly, David Stronach and John Haxton served as the embassy's botanical gardeners.