"(Winning) is the one thing I came here for and I have not delivered that to this organization or the football team; for that I apologize," Jackson said Monday. "I promise you this: I am going to do everything in my power from this moment on with the help and resources within our organization to get this organization turned to winning.
"I understand the disappointment that all feel right now because I think we are all working through it, but I know one thing, we are going to do everything we can as an organization to get the Cleveland Browns to where we feel they are a winning football team."
Jackson also said he is "grateful and thankful" that owners Dee and Jimmy Haslam are having him return to coach in 2018, fresh off the Browns becoming the second NFL team to post a winless campaign in a 16-game season. The 2008 Detroit Lions also went 0-16.
"This is going to stay next to my name, this organization's name, this team's name for the rest of our lives," the 52-year-old Jackson said after the Browns' 28-24 season-ending loss to the Pittsburgh Steelers on Sunday.
Jackson also said on Monday that he plans to spend the next few days reflecting on potential changes to his staff, including the possibility of hiring an offensive coordinator.
Jimmy Haslam fired vice president of football operations Sashi Brown on Dec. 7 but decided to keep Jackson despite his now 1-31 coaching record with the Browns.
Haslam hired John Dorsey as general manager the same day he fired Brown. Brown bequeathed Dorsey two first-round picks, three second-round picks in 2018 and more than $100 million in salary cap room.