Deceuninck-QuickStep’s Elia Viviani managed to finish second in the 145km stage, with Bora-Hansgrohe’s Rüdiger Selig completing the podium.
In the final 2km CCC’s Francisco Ventoso attacked, but the peloton was on his tail as he passed under the 1km to go mark.
A crash in the peloton then caused Bora-Hansgrohe’s Pascal Ackermann, who has won two Giro stages, and CCC’s Jakub Mareczko to go down, which resulted in FDJ leading the sprint and Démare ultimately taking the victory.
“I saw the crash coming through there after with a few of the sprinters on the ground. I came through a bit later as I had done my work earlier and I think Arnaud kept ahead of it and safe so that’s good,” said the stage winner’s teammate Miles Scotson.
“My role was to make sure a big break didn’t go and it was only two guys, so after that just controlling it and making it come back not too early and not use an extra guy.
“The job today wasn’t too hard compared to last week but I think I had the motivation to really work as a team and try again, it’s super.”
Shortly after the start of the flat and short stage, Luca Covili (Bardiani-CSF) and Sho Hatsuyama (Nippo-Vini Fantini), who are both riding their first Giro, were the first breakaway of the day.
They had a maximum lead of over four minutes, which quickly narrowed down to two, before the peloton caught them with less than 30km to go.
The peloton were gruppo compatto until the attacks occured in the final kilometres.