The men's 49er was a sailing event on the Sailing at the 2012 Summer Olympics program in Weymouth and Portland National Sailing Academy. Sixteen races were scheduled and completed. 40 sailors, on 20 boats, from 20 nations competed. Ten boats qualified for the medal race on course area Nothe in front of Weymouth, where each position scored double points.

The 49er and 49er FX is a two-handed skiff-type high-performance sailing dinghy. The two crew work on different roles with the helm making many tactical decisions, as well as steering, and the crew doing most of the sail control. Both of the crew are equipped with their own trapeze and sailing is done while cantilevered over the water to the fullest extent to balance against the sails.