The Dutch right-back had been on trial at the Satergate club after failing to impress Huddersfield Town.
Uhlenbeek said: "Although I had a few other options, Roy McFarland sold the club to me. I am very happy with the players I have seen here and we could be in for a good season.
"I am still ambitious and want to win things so to end as high as possible in the division with Chesterfield is my personal target for the season."
Chesterfield Manager Roy McFarland added: "We have worked hard on this so I am pleased Gus has chosen to come to Chesterfield despite competition from some other clubs.
"From day one we have been looking for someone to fill the right-back spot and it looks like we have got our man."