The 35-year-old centre-back has joined City on a free transfer after leaving Brighton, and has signed a one-year contract.
"It is a great opportunity and something I am very grateful for," said Upson.
"It is a chance to play in the Premier League again, which was something I have been striving to do since I stepped down into the Championship. From that point of view it is a great opportunity.
"I played against Leicester last season and I liked the way the team played and the intensity they had.
"I have been very impressed with the manager. He seems very straight with the players.
"He knows what he wants and there is a great attention to detail here.
"It seems very organised, so I think I will enjoy playing here."
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