Groenen has signed a pre-contract agreement with the club to join this summer from German club FFC Frankfurt, where she has been playing since 2015. United have promised to give further details when the deal is finalised and completed.
For United, who only formed last summer, it is a significant statement of intent to sign someone of the quality and reputation of Groenen as they prepare to make an impact in the WSL.
Groenen is the club's first overseas player, with the squad exclusively made up of English and Scottish players during the 2018/19 campaign.
She made her international debut for the Netherlands in 2016, was a key member of the Oranje team that won Euro 2017, and is part of the World Cup squad heading to France next month.
United fans will be able to catch an early glimpse of Groenen in action at the tournament, with the Netherlands drawn into a tough group alongside Canada, New Zealand and Cameroon.
She is already the second Dutch international to commit to a WSL club ahead of next season, with Arsenal announcing the signing of Jill Roord from Bayern Munich earlier this month.