Bishop McKeown was appointed Bishop of Derry in 2014, with Michael Router installed as his successor on Sunday.
The former SDLP leader said: “I would like to take this opportunity to thank Donal McKeown for his service to the people of Derry and wish him a long, healthy and happy retirement.
“For more than a decade, Donal has been a pillar of our community and at the heart of life in the city through good times and difficult times. He has celebrated our successes and shared in our sorrows, always showing a genuine commitment to the people he served.
“He has been Bishop during a period of significant change for our city and has shown real leadership when it was needed. I have encountered him at many events over the years and have always appreciated his kindness, warmth and dedication to his role.
“The fact that Donal intends to remain in the area during his retirement is a reflection of the relationship he has built with the city and the place he has earned in the hearts of so many people.
“I would also like to wish Michael Router every success as he takes on his new role. It is fair to say he has big shoes to fill, but this is also a huge opportunity and I know the people of Derry will offer him a warm welcome and every support as he begins his ministry here.”