It will publish news about her work as ambassador for the Geneva-based Global Fund to Fight Aids, Tuberculosis and Malaria, as well as giving information about her French foundation.
The new site was overwhelmed with traffic after it was publicised on the French news and would-be viewers saw a message in French suggesting that they tried again later.
41-year-old Bruni married President Sarkozy last year after a much-publicised romance.
Besides her new website the former super-model has another site devoted to her work as a singer.
