PORT Adelaide star Robbie Gray is destined to finish his career as a one-club player after signing a one-year contract extension until the end of 2021.

The three-time Power best and fairest and four-time All-Australian – who turns 32 on March 30 – was set to be an unrestricted free agent at the end of this season before agreeing to the new deal.

"It's a nice feeling to sign another contract extension," Gray said.

"I'm grateful for the opportunity Port Adelaide has given me, and to extend my time here for another year is great for me and my family."

Gray has played 218 games for the Power since being taken with the 55th overall pick of the 2006 NAB AFL Draft.

He claimed three straight John Cahill Medals from 2014-16 and earned All-Australian honours in 2014, 2015, 2017 and 2018.

Gray also holds the record for the most Showdown Medals, having been awarded best and fairest in a Showdown on five occasions.

The Power's general manager of football Chris Davies said it was great to secure the skillful forward for another season.

"Rob has been an outstanding player for our team over a long period of time now," Davies said.

"However, his importance to our club, both on and off the field, cannot be overstated.

"He's had a strong pre-season, and has provided amazing assistance for our young group."