The South Yorkshire club were second in the League One table when Saunders left to take over at Championship strugglers Wolves.
Scout Brian Flynn was handed the reins on a temporary basis before being given a contract until the end of the season, and the former Wales boss continued Saunders' good work by steering Doncaster to promotion as champions.
Ryan said: "I must pay tribute to Dean Saunders.
"He put this team together and made some great signings - like Rob Jones and David Cotterill who have both been named in the League One team of the year.
"It was difficult circumstances in the summer after relegation but he left us in a great position and his contribution should certainly not be forgotten."
Ryan added: "I must also pay tribute to Brian Flynn who took it on and finished the job.
"Those two, the whole squad, can be proud of what we have achieved."