Van't Geloof joins from Ale Cipollini, with whom she's this season taken third place at the Trofee Maarten Wynants and eighth at the Nokere Koerse. The previous year, she'd ridden for Lotto Soudal Ladies.
"I'm very thankful for the opportunity that the team has given me," Van't Geloof said in a press release. "They kept believing in my abilities even though I wasn't really in the position to show them this season. I can be a strong part of the team in the spring Classics and the flat races.
"The spirit of this team is inspiring to me," Van't Geloof continued. "The fun and joy that cycling has brought me over the years is really important to me. So, for sure, I am going to enjoy the next season to the fullest."
Drops team director Bob Varney added: "Marjolein is a great talent, and it's now down to us to help her realise that talent. With the roster we've lined up for 2020, we aim to be strong in the semi Classics and sprint stages, and Marjolein will be a key part of that focus next season."
The news of Van't Geloof's signing comes soon after the team also signed Norwegian duo Emilie Moberg and Elise Marie Olsen for next season.