The O'Callaghan's Mills clubman - who made his championship debut for the Banner against Cork in 2006 - has made the announcement today.
Donnellan commented: "I wish to sincere thank everyone that has helped me and made sacrifices on my behalf to ensure that I could represent Clare to the best of my ability. To my wife Edel, my parents, my brothers and sister I will be forever grateful.
"I will always consider myself a privileged person to have been able to play for Clare and I hope that I did my utmost for the cause while playing. It is hard to express in words what it meant to me, my family and my club to captain a Clare team.
"To be able to lift the Liam McCarthy on behalf of Clare and its people was a dream come true and I will always be thankful that I was considered worthy of the honour to be the representative of the Clare team by Davy Fitzgerald.
Patrick Donnellan in action during the drawn 2013 All-Ireland final clash against Cork. ©INPHO/Ryan Byrne.
"Thank you to my club O'Callaghan's Mills, to all of my former managers and coaches who instilled a love and respect for the game in me every day I took to the field. Thank you to Clare County Board, Club Clare Hurling Supporters and to all of the backroom staff who encouraged and supported me throughout my time with Clare. Thank you also to my employers and work colleagues in IAC for the wonderful support.
"I would like to thank all of the players that I have played and trained with over the years. I always felt a sense of belonging and brotherhood in a Clare dressing room and I have been lucky to be friends and teammates with you all.
"Finally, I am looking forward to supporting the team from the stands into the future and I wish the Clare team and management all the best for 2018 and onwards. An Clár Abú!"