Drivers will now be restricted in the number of changes they can make to their helmet design during each season, meaning fans both at the track and those watching on television will be able to recognise them more easily.
The rule was voted through in January this year, and has now been formally adopted in the FIA's 2015 F1 Sporting Regulations.
The revised article reads: "In order for drivers to be easily distinguished from one another whilst they are on the track, the crash helmet of each driver must be presented in substantially the same livery at every Event during a Championship season."
The FIA also moved to clarify what happens to a driver's number once cease competing in F1. While drivers have to pick a permanent number for their entire career, their number will become available again should they not compete for two entire consecutive seasons.