A mobile object control system includes: a storage device configured to store instructions; and one or more processors, wherein the one or more processors execute the instructions stored in the storage device to: acquire an image in which a road where a mobile object is present is imaged; recognize support information for supporting movement of a specific traffic participant who is a traffic participant having a predetermined attribute appearing on a road surface included in the image; recognize a road structure included in the image or a road structure which is a structure provided on the road; move the mobile object at least based on a trajectory determined using the support information when the support information is recognized; and move the mobile object based on a trajectory determined using the road structure without using the support information when the support information has not been recognized.