He accompanied Lord Amherst on his mission to China in 1816-17 as the embassy's chief medical officer and naturalist, on the recommendation of Sir Joseph Banks. The mission was Britain's second unsuccessful attempt to establish diplomatic relations with China and involved travelling to the capital Pekin (Beijing) and the famous botanical gardens of Fa Tee near Canton. While in China, Abel collected specimens and seeds of the plant that carries his name, Abelia chinensis, described by Banks' botanical secretary Robert Brown, "with friendly partiality". However a shipwreck and an attack by pirates on the way back to his home in Britain caused him to lose all of his specimens. Abel's Narrative of a Journey in the Interior of China, 1818, gives a detailed account of the collection's misfortunes. Fortunately, he had left some specimens with sir George Staunton at Canton, who was kind enough to return them to him; living specimens of the Chinese Abelia that we know today were introduced by Robert Fortune in 1844.
Abel was the first Western scientist to report the presence of the orangutan on the island of Sumatra; the Sumatran Orangutan Pongo abelii Lesson 1827 is named for him. He went on to become the surgeon-in-chief to Lord Amherst when the earl was appointed Governor-general of India. Abel died at Cawnpore, India, 24 November 1826, aged 37.