Amberley was pressured by his father to take up politics, and his friend, the philosopher John Stuart Mill MP, expected him to become his political heir. Following an unsuccessful 1865 candidature at Leeds, he was elected Member of Parliament for Nottingham on 11 May 1866. A progressive Liberal, he served until 17 November 1868. Amberley's religious views presented a great obstacle to his political career, with even Liberal clergymen angered by his refusal to observe Sunday. He also advocated birth control as means of countering overpopulation and public health issues, for which he was accused of depreciating marriage, supporting abortion, and insulting physicians. This stance cost him a seat in the South Devon election in 1868. Following this defeat, he gave up his parliamentary career, but continued to write and speak in favour of women's suffrage.