The Colombian climber turned professional with the Colombia-Coldeportes team in 2012 and moved up to the WorldTour with BMC Racing Team in 2014 before moving to UAE Team Emirates in 2017.
The 30-year-old finished ninth overall at the Giro d'Italia in 2016, and won a stage of the Tour de Suisse a month later. He has become a regular fixture in breakaways on Grand Tour mountain stages, but has yet to land a stage win despite a string of near misses.
"I'm both happy and proud to be able to wear the Cofidis colours from next January. I've already got back into training in order to be ready for the first team meetings," Atapuma said.
"It's a great experience for me to be in a French team. I already know some of the riders and I don't doubt for an instant that, thanks to the team spirit, we can continue to win races and put in excellent performances."
Cofidis' chief breadwinners in the past couple of seasons have been sprinters Nacer Bouhanni and Christophe Laporte. The team signed the Herrada brothers from Movistar last year for added versatility, and manager Cedric Vasseur feels that the acquisition of a pure climber in Atapuma makes his squad a complete one.
"I'm extremely happy and proud to be able to welcome a rider of this quality to our squad. With Darwin, I'm convinced we're now equipped to shine and win across all terrain. It's the link we've been missing in the last few years," Vasseur said.
"With the experience gained at WorldTour teams, he is capable of showing himself at every opportunity. And above all we have found in him a rider who can shine on climbs that go above 2,000 metres, as we will see on numerous occasions in the next Tour de France. So I can't wait to welcome him along with the other newcomers, and I'm convinced he'll allow us to take another step forward."
In leaving UAE Team Emirates, Atapuma follows Ben Swift, (Team Sky), Filippo Ganna (Team Sky), and Przemysław Niemiec (retirement), while the team have brought in Colombian sprinter Fernando Gaviria from Quick-Step Floors along with a number of neo-pros, including Tour de l'Avenir champion Tadej Pogacar, Juan Sebastián Molano, Christian Muñoz, Alessandro Covi, and the Oliveira brothers, Rui and Ivo.
Atapuma is Cofidis' seventh signing for the 2019 season, following Zico Waeytens (Veranda's Willems-Crelan), Jesper Hansen (Astana), Marco Matthis (Katusha-Alpecin), and neo-professionals Damien Touzé, Filippo Fortin and Victor Lafay. Leaving the team are Jimmy Turgis (Vital Concept), Anthony Turgis (Direct Energie), and Daniel Navarro (Katusha-Alpecin).