He was admitted as a barrister in Hong Kong in a ceremony that May before Chief Justice John Smale who observed: I am glad to see a Chinaman running in the race the most highly intellectual in the world.

[5]: 262 In 1880, Wu became the first ethnic Chinese Unofficial member of the Legislative Council of Hong Kong[5]: 297  and was appointed acting Police Magistrate.

[5]: 303 He served under the Qing dynasty as Minister to the United States, Spain, and Peru from 1896 to 1902 and from 1907 to 1909, having started out as legal adviser and interpreter to powerful diplomat and viceroy Li Hongzhang.

For example, on 21 November 1903: "Wu Tingfang came in the afternoon, and stopped talking for an hour and a half about his commercial code and connected subjects.

His efforts included modernising the criminal code and abolish inhumane methods of capital punishment such as death by a thousand cuts, decapitation and posthumous execution, and use of torture in interrogations.

[9] In an interview with American journalist Marguerite Martyn, Wu Tingfang argued in favor of women's suffrage.

He served briefly in early 1912 as Minister of Justice for the Nanjing Provisional Government, where he argued strongly for an independent judiciary, based on his experience studying law and travelling overseas.

[15] Wu abstained from alcohol and tobacco after reading Mary Foote Henderson's book The Aristocracy of Health.

[16][17] He gave speeches on vegetarianism and authored an article "How I Expect to Live Long", published in November 1909 for the Ladies' Home Journal.

[18] Wu also established a vegetarian restaurant known as Micaili in Shanghai at Hotel des Colonies in the French Concession (now on East Yan'an Road).