[1] Billault was elected deputy on 4 November 1837 for the constituency of the Lower Loire (Aucenis), taking his seat on the left and voting with the opposition.

He was reelected on 2 March 1839 and accepted the position of Deputy Secretary of State of the Ministry of Agriculture and Commerce, under the minister Alexandre Goüin.

[1] After coming to fully agree with the policy of Louis-Napoléon Bonaparte, Billault became a frequent visitor to the Élysée Palace.

In this role, on 1 December 1852 Billault went to the Château de Saint-Cloud to bring the results of a plebiscite which had voted in favor of restoring the empire, with Louis-Napoléon as the Emperor Napoleon III.

He remained in office until the crisis caused by the assassination attempt by Felice Orsini, when he was replaced by General Charles-Marie-Esprit Espinasse on 8 February 1858.

When Napoleon III tried to inaugurate the liberal empire on 24 November 1860, he called on Billault to serve as minister without portfolio.