Mullen, who made his debut for the Knights in 2005 and has since played 172 games, is happy to re-sign with the Club he's always supported.
"This is the Club I started playing my NRL career with and the Club I want to finish it at, so I am very pleased to re-sign," Mullen said.
"I really thank the Club for this opportunity because I never wanted to go anywhere else.
"There are not many players that can play their career out at the one Club. I will be 31 when I finish this contract, but hopefully I can keep going after that and finish my career here as I said.
"To even get an opportunity to play first grade for the Knights was a dream come true, and it is ten years I have been here now, so you have to sit back and pinch yourself sometimes because you are out there playing first grade in front of your friends and family."
Coach Wayne Bennett is pleased Mullen has committed long-term to the Knights.
"At this Club we want the kids that have been brought up here to stay here and we are building towards that," Bennett said.
"We want to offer them their retirement if that is possible and Jarrod is obviously in that category.
"Anyone that saw Jarrod's performance on Saturday, would realise what he brings to this team and why he is so valuable.
"To get injured during the pre-season and come in at round six and play like he did on the weekend, he is certainly above the average."
Despite finishing in the top three of the Club's Best and Fairest in 2013 and in the top five of the Dally M Awards, Bennett believes Mullen's best football is ahead of him.
"Jarrod is in that category of elite players that probably has every skill in the book," the coach admitted.
"I think he is learning to play with a lot more calmness now and that is what we need him to bring to the team.
"He is really maturing as a player and as we have seen, five-eighth is definitely his position.
"Who knows what is in front of him? From my point of view, he is getting better every season."Like