A member of a team that worked on FHM's recent redesign, Brown joined the magazine in 1998. He was the features editor for two years.
Brown takes the editorial helm at FHM as it faces a testing time following the launch of the men's weeklies Nuts, Zoo and Cut. Its circulation is 573,713, down 4.5 per cent year on year.
He said: "There has never been a more exciting time to edit FHM. The arrival of the weeklies earlier this year has transformed a relatively calm men's market into a seething battleground."
The magazine's redesign, which includes a new-look cover and the introduction of more editorial sections, was introduced last month after a ten-month period of consumer research. It is backed by a three-month burst of advertising through NMI.