The Dutch midfielder has completed her move from German side FFC Frankfurt and, in doing so, has become the first overseas player to join Casey Stoney's side.
Despite being just 24 years old, Groenen has a wealth of experience and has already played in England with Chelsea Women, while amassing 54 caps for the Netherlands national side.
She played a pivotal role for the Dutch at the Women’s World Cup in France earlier this summer, featuring in all seven games for the eventual runners-up and netting the winner against Sweden in the semi-finals.
Groenen is hoping she can bring her winning mentality to United ahead of our first campaign in the Women’s Super League.