Attacking midfielder Nolan has left West Ham by mutual consent after four years at the London outfit.
During his time at the Boleyn Ground, the former Bolton Wanderers and Newcastle United star played 157 games, scoring 31 goals in the process.
Collison, who played with Nolan at West Ham, has posted an emotional tribute to the 33-year-old on Twitter.
Good luck to this man for the future... He's influence has been massive on & off the pitch for West Ham..True Gent. pic.twitter.com/4oQYmbiDTO— Jack collison (@Jcollison31) August 28, 2015
Nolan had been on the books of West Ham since 2011, but he struggled to make a huge impact last season.
The former Newcastle attacking midfielder scored just one goal and created only 12 chances in 29 Premier League appearances during the 2014-15 campaign.
The 33-year-old had a pass accuracy of 78% and a shot accuracy of 52%, and won 22 headers, four dribbles and 28 tackles.