Greenwood clashed heads with Belgium forward Jassina Blom in the 19th minute and was treated on the pitch for almost 12 minutes.
Four members of England’s staff treated the centre-back, while they were assisted by six medical personnel at the King Power at Den Dreef Stadion in Leuven.
Greenwood was eventually carried off the pitch on a stretcher and with a neck brace on, while receiving oxygen. She was given a standing ovation by the supporters in Belgium.
There was concern among the defender’s England team-mates, who stood around her and followed her off the pitch.
It was confirmed at half-time that Greenwood was conscious and talking, and by the end of the game manager Sarina Wiegman revealed she was up and walking and "doing fine" but had suffered a suspected concussion.
“She’s fine,” said Wiegman. “I haven’t spoken to her yet. I also haven’t spoken to the doctor about it yet, but I heard she’s walking around, I didn’t see that.
“I heard she’s walking around, and she is okay, but obviously she has a concussion, but it’s good news just that she’s walking around and doing fine."
England were 1-0 down when Greenwood was taken off in the 32nd minute and replaced by Jess Carter.
The Lionesses fought back and took the lead through goals from Lucy Bronze and Fran Kirby.
Belgium got back on level terms before the break, however, as their captain Tessa Wullaert struck during the 14 minutes of injury time.
Belgium then claimed all three points late on when Wullaert struck a penalty, meaning England have slumped to third in Nations League Group A1.