In 2013, Démare won 3 stages in a row at the Four Days of Dunkirk and the general classification. On the third stage, his team-mate and lead-out rider Geoffrey Soupe produced a final power surge to launch Démare, and the duo finished one-two in the mass sprint, with Ramon Sinkeldam of taking third place.
2014 season
Démare won the Four Days of Dunkirk stage race for the second year in succession, winning two stages during the event. He also won the points and young rider classifications. He also put in some strong performances in the cobbled classics, finishing second in Gent–Wevelgem and twelfth in Paris–Roubaix.
In January 2016 Démare announced his race plans for the first half of the new season, starting his campaign on home soil at the Étoile de Bessèges and Tour Méditerranéen, followed by competing in the cobbled classics of Omloop Het Nieuwsblad, Kuurne–Brussels–Kuurne, Milan–San Remo, Gent–Wevelgem, Tour of Flanders and Paris–Roubaix, along with the stage racesParis–Nice and the Three Days of De Panne. He also announced that he would skip the Tour de France and focus on the Giro d'Italia instead. He enjoyed success at the Tour Méditerranéen, where his FDJ squad won the race's opening team time trial and he won the following stage. Démare went on win the first full stage of Paris–Nice and then took the biggest win of his career at the Milan–San Remo. His victory was questioned by rival riders Matteo Tosatto and Eros Capecchi, who alleged that Démare had been assisted by a tow from a team car on the climb up the Cipressa after he crashed with to go. However, in the absence of any photographic or video evidence, race officials decided not to take any action. Démare became the first Frenchman to win the Milan-San Remo since Laurent Jalabert in 1995. He was also the first Frenchman to win a Monument race since 1997, when Jalabert and Frédéric Guesdon had won the Giro di Lombardia and Paris–Roubaix respectively.
2017 season
On July 4, two days after finishing Stage 2 in second position behind Marcel Kittel, Démare clinched his first Tour de France or Grand Tour stage win by winning the Tour de France's fourth stage that ended in a hectic sprint into Vittel; it was the first stage victory by a Frenchman in a bunch sprint since Jimmy Casper won Stage 1 that started and ended in Strasbourg in 2006. In Stage 6, Démare was edged out again into a second-place finish by Marcel Kittel, who launched a perfectly timed late sprint with around 200 metres to go. Démare was ill during the mountainous Stage 8 and fell back very early. Two teammates were with him to try and bring him in within the time limit. He eventually finished in 188th position, 37 min 33 sec behind the Stage 8 winner. Démare, who was sitting in second position in the points classification at the start of the Stage 9, finished that challenging mountain stage in a group around 40 minutes behind the Stage 9 winner. That put him outside the time limit, and therefore out of the Tour de France, along with six other riders.
2019 season
Démare was taking part in the long-range, high-speed bunch sprint when he timed his move to perfection less than a kilometre from the finishing line to win stage 10, which ended on the streets of Modena, of the Giro d'Italia, his first ever Giro stage win.
