The Greater Western Sydney GIANTS have agreed to release Mark Williams from the final year of his contract as Senior Assistant Coach of the GIANTS.

GIANTS Chief Executive David Matthews said Williams had informed the club of his decision to move to Melbourne for family reasons.

"Mark has made an outstanding contribution to the GIANTS over the past two years and has been a brilliant teacher to our young players and we want to thank him for everything he has done for our club," Matthews said.

"He has a young family and we have always said we would not stand in his way should he wish to pursue an opportunity elsewhere and we wish him all the very best for the future."

The GIANTS announced on Tuesday that Head Coach Kevin Sheedy had been reappointed for 2013 and Matthews said the departure of Williams was an opportunity for the club to review its coaching structure under Sheedy next year.

"We are in the fortunate position of having a number of very capable assistant coaches in Luke Power, James McDonald, Dean Brogan and Alan McConnell and we will look to further strengthen our coaching panel as we head into 2013," Matthews said.

"Nearly half of our playing list is now committed to the club on long term contracts with the re-signings this week of another eight of our young stars including Jeremy Cameron, Toby Greene, Adam Treloar and Stephen Coniglio among others.

"We've shown in our inaugural year that we play a tough, competitive and exciting brand of football and I'm sure there will be huge interest in the GIANTS from prospective coaches around Australia."