Sarah Hebert, a four-times French windsurfing champion and European champion, began her 4,000 kilometre (2,485-mile) journey from a beach north of the capital Dakar. She is expected to take 25 days to reach the Caribbean island of Guadeloupe.
The 28-year-old from Carnac, in Brittany, northwest France, was fitted with a pacemaker after a routine medical check-up discovered an underlying heart condition.
Hebert is being accompanied by a support boat with a four-man crew. She intends to windsurf for six to eight hours a day and sleep on board the craft every evening.
The boat is also carrying four replacement boards, a dozen extra sails, a VHF radio, satellite telephone, a global positioning system as well as distress flares and beacons.
She will restart her journey every day using the GPS to plot the exact point where she stopped the previous evening. The windsurfer has said she will listen to music during the crossing, as well as audio books by the author Jules Verne.
Hebert's progress across the Atlantic can be followed on a dedicated website.