Antoine-Florent Guillain (7 February 1844 – 19 April 1915) was a French maritime engineer who designed a major upgrade to the port of Dunkirk, and rose to be Minister of Public Works.

[1] In 1888 Guillain was made director of Roads, Navigation and Mines in the Ministry of Public Works.

In 1891 he was appointed inspector general of public works, and in 1893 was given responsibility for the national roads of France.

[1] In 1893 Guillain was elected to the general council of the Nord department as representative of the canton of Dunkirk East.

On 13 December 1896 he ran as Progressive Republican candidate in a legislative by-election for the first district of Dunkirk, and was elected in the first round of voting.

[2] In 1902 Guillain became chairman of the Compagnie Francaise Thomson-Houston (CFTH), a large electrical company, replacing Émile Mercet.