A dental floss dispenser cap for attachment to a toothpaste tube. The dental floss dispenser cap according to certain embodiments of the invention, comprises a housing and an annular base. Upstanding walls form a cylindrical protrusion and a cavity dimensioned to receive the cap of a toothpaste tube underneath. A spool of floss may be placed on the cylindrical protrusion for rotation and dispensing. A cover may be attached to the housing by a first hinge. The cover preferably comprises a notch opening for the dental floss to pass through and a metal cutting member such as a lance mounted to the cover. A lid may be attached to the cover by a second hinge. The lid can be opened and closed to access the dental floss and protect it from contamination when not in use as desired.