United are desperate to make a big name signing and see the English winger as the ideal candidate.
But the 20-year-old has a contract at Borussia Dortmund until 2023, and the German giants want 120 million euros for his signature.
"He's fantastic," said Ferdinand on BT Sport.
"If he comes I think he'll be an added value in terms of quality, no doubt.
"Manchester United should be in the market for the best players in the world.
"They need to sign top players who are going to have an effect on their first-team and Jadon Sancho falls into that category.
"If you look at successful Manchester United sides over the years, successful periods, there were players fighting for every position and if you substituted one out and you brought one in, there was no change in the quality or the output.
"If you add someone like him to the team, that is the case when he's there, so he's a fantastic player."