The 23-year-old, who came through the ranks at Crystal Palace and also counts Bolton Wanderers among his former clubs, penned a deal at Meadow Lane on Thursday.
Nolan told the official club site: "Ross has a lot of great attributes and we think we can work with him to make him even better.
"He had a good season with Chelmsford last year and getting back into the EFL is a huge boost for him. We believe he can push Adam Collin for the number one spot.
"We wanted competition for places and Ross ticks all of the boxes. He has settled into the group well.
"Mark Crossley has had a number of goalkeepers in on trial during the summer and Ross has been one of the standout candidates.
"I trust Mark with everything when it comes to goalkeepers because his knowledge is second to none."
Share your thoughts about this news story on Pride of Nottingham by signing up to the website, visiting the forum and joining in the chat with hundreds of fellow Notts County fans.
We at Pride of Nottingham want you to enjoy all our content for free. If you fancy helping us provide even better content, however, please consider contributing to PON by clicking here!