Bonnet served in the Chamber of Deputies from 1924 to 1928 and again from 1929 to 1940. He was appointed undersecretary of state in 1925, the first in a series of high ministerial positions throughout the 1920s and 1930s. During his time as in the Chamber, Bonnet was regarded as a leading expert in financial and economic matters. As a minister, Bonnet had a reputation for hard work, always being well prepared in parliamentary debates and excelling at political intrigue. In 1932, Bonnet headed the French delegation at the Lausanne Conference. During the Lausanne Conference, British Prime Minister Ramsay MacDonald, commenting on Bonnet's abilities, asked: "Why isn't he in the Cabinet?".