After nearly three weeks, clearance has finally been granted and Niskanen looks set to make his debut against St Mirren on Saturday.
United tweeted: “Following the completion of the work permit process, we are thrilled to confirm the Ilmari Niskanen has officially arrived at Tannadice.”
Niskanen told the club: “I’m absolutely thrilled to be here and really looking forward to getting going.
“I’m a powerful, fast, dynamic winger. I know if I put my full potential out then I can be a good player here.
“I want to help the team achieve the best position in the table as possible. We have a strong team so I know we can do really well this season.”
Ilmari Niskanen: New Dundee United winger finally able to make debut as work permit confirmed