Officials have described the scheme as a "knowledge programme" which will provide the department with a global pool of information via a secure intranet.
A spokesman for the FCO said, "One of the aims of the project is to get better information to our staff so that they can help ministers and the public better."
The service is designed to cut down on information overload and keep decision-makers in both Whitehall and the FCO up to date with accurate information. It will encompass the FCO's 14,000 staff, who are based in more than 200 offices worldwide.
The FCO spokesman said, "The Foreign Office has traditionally been very good at keeping electronic records, but they are currently kept in separate document stores around the world."
Officials estimate the FCO will be storing between one and two terabytes of information within five years.
Documentum's 4i platform will be used for content management as part of the deal.