Buxton was educated at Harrow School and Trinity College (1886–9). At Cambridge University he gained a third in the historical tripos. In 1889 he went to work at the family brewery in Spitalfields. He was shocked by the poverty he encountered and became involved in social work through the settlement movement.
He joined the Liberal Party and in 1897 he became a member of the Whitechapel board of guardians. He also contributed an essay on the problems of city life, to The Heart of the Empire, a book edited by Charles F. G. Masterman. In 1900 General Election he was unsuccessful in his first parliamentary contest in Ipswich, but was elected to parliament for Whitby at a by-election in 1905, only to be voted out again the following year in the the 1906 General Election.
Buxton was elected Liberal MP for North Norfolk in January 1910, and while campaigning in the constituency he met his future wife, Lucy Edith Burn at the time she was canvassing on behalf of his political opponent. The couple moved to Paycockes, a house at Coggeshall in Essex.
He supported Britain's involvement in First World War and even voted for conscription. However, he argued that "the prosecution of the war should be conducted in the diplomatic field as well." After the overthrow of Tsar Nicholas II in Russia, socialists in Britain, France, Germany, Austria-Hungary, United States and Italy called for a conference in a neutral country to see if the First World War could be brought to an end. Eventually, it was announced that the Stockholm Conference would take place in July 1917. Arthur Henderson was sent by David Lloyd-George to speak to Alexander Kerensky, the leader of the Provisional Government in Russia. However, under pressure from President Woodrow Wilson, the British government had changed his mind about the wisdom of the conference and refused to allow delegates to travel to Stockholm. As a result of this decision, Henderson resigned from the government.
Buxton became very disillusioned with these developments and he now joined the Labour Party. His biographer, C. V. J. Griffiths has argued: "His social conscience and commitment to charitable work remained constant features in his life, and from 1919 onwards he directed part of his income to the achievement of social and economic progress through a special trust administered by the family."
In the 1923 General Election, the Labour Party won 191 seats. Although the Conservative Party had 258 seats, Herbert Asquith announced that the Liberal Party would not keep the Tories in office. If a Labour Government were ever to be tried in Britain, he declared, "it could hardly be tried under safer conditions". Ramsay MacDonald agreed to head a minority government, and therefore became the first member of the party to become Prime Minister. MacDonald had the problem of forming a Cabinet with colleagues who had little, or no administrative experience. MacDonald's appointments included Buxton as Minister of Agriculture. A post he held until the fall of the MacDonald government in October, 1924.
In the 1929 General Election the Labour Party won 288 seats, making it the largest party in Parliament. MacDonald became Prime Minister again, but as before, he still had to rely on the support of the Liberals to hold onto power. Buxton became Minister of Agriculture in the new government.
Baron Noel-Buxton was chairman of the Anti-Slavery and Aborigines Protection Society, president of the Save the Children Fund (1930-1948) and president of the Miners Welfare Fund (1931-1934). He was a supporter of appeasement, arguing that Germany must be given a colonial role in Africa. During the Second World War he promoted the policy of a negotiated peace with Nazi Germany.
He (Buxton) voted for conscription, and worked in the Admiralty. He believed the war should go on if an honourable peace could not be concluded, but that " the prosecution of the war should be conducted in the diplomatic field as well." That was a way of saying that the rulers of Europe should find out at intervals on what terms the combatants were prepared to make peace. Thus he presented his idealism in the dress of common sense - the only way of making your voice heard in those savage and blind days. His public meeting at the Central Hall, Westminster, in 1917, on his return from Washington, when he announced the terms of the German peace offer of 1916, was described by the Nation as the turning-point in the development of moderate and sane opinion. From that time on, the peace movement gathered new force and assumed a more practical shape. The atmosphere was prepared for the famous Lansdowne letter.
He lost his seat in the Khaki Election of 1918, but only by 200, while his friends lost by many thousands. He joined them in the wilderness and became a member of the Labour Party. It is characteristic of the man that the Labour Party is not only his spiritual home, but also his natural home. He may not look the part. The intriguing distinction of his appearance has made people compare him to a Cardinal, to an Elizabethan courtier, or to a figure out of Van Dyck portraits. But his tastes are simple, and in spite of his wealth his living plain. He did not break with "society" when he apparently burnt his political boats, because he had always avoided the circles of fashion. Indeed nothing gives him greater pleasure than to spend a week-end in a workman's cottage in the pretty little village of Upshire which looks down on the stately manorial home of his childhood. Even as a Cabinet Minister he regarded a week-end so spent as one of the cherished luxuries of life. On a Saturday in long waders, knee deep in a pond which adorns his garden, he can often be seen thinning out the rushes. Digging and hoeing or planting young trees are a passion with him.