Square Mile is a monthly glossy distributed to those working in the City of London. The title, which is published by Square Up Media, has been going since 2005.
The first style issue will be published in February next year.
Style guru Jeremy Langmead will be among contributors to the issue. One of the main features will cover the changes in taste in men's fashion in the City, from the yuppie era to the present day.
Square Mile prints 50,000 copies every month and is distributed every first Tuesday.
In a further move to heighten the brand's reputation, Square Mile is also launching its own awards, to find the most stylish man and woman in the City.