Mark Mishek plans to retire in 2021 after a more than 12-year run as Hazelden Betty Ford Foundation’s top executive.

Mishek will stay on as chief executive until his successor is hired, the alcohol and drug addiction treatment clinic said Wednesday in a news release.

“While I’m excited about the next chapter in my life, I’m equally excited about the future of Hazelden Betty Ford and know that our mission is more important than ever before,” Mishek said in a prepared statement.

Mishek became president and CEO of the Hazelden Foundation, based in Center City, in 2008 and led the 2015 merger of Hazelden and Rancho Mirage, Calif.-based Betty Ford Center.

Today, the combined organization operates 17 sites. A spokesman said the search for Mishek’s successor begins next week and a new CEO is expected to be hired in the first half of 2021.

During Mishek’s tenure, the organization has more than doubled the number of patients it serves yearly as it has moved away from a self-pay model and gained in-network status from major health plans.

“Mark not only brought two storied institutions together and significantly expanded our presence, but he also made our lifesaving care accessible to millions more people,” said Lester Munson, who chairs the Hazelden Betty Ford Foundation board of trustees.

Mishek is credited with redefining abstinence-based treatment and leading the effort to develop an innovative approach to opioid addiction in 2012 that combined medication and psychosocial therapy.

In 2019, Hazelden Betty Ford and the Mayo Clinic said they would collaborate on a federal research project to study genetics and response to a drug used in addiction treatment.

Before joining Hazelden in 2008, Mishek, who is a recovering alcoholic, was president of United Hospital in St. Paul, and had worked for 20 years with the Allina health system.

“Mark knows personally — like I and countless others do — what it’s like to have addiction, and then recovery, in the family, and is driven by a determination to help as many people as possible,” said Susan Ford Bales, trustee for the Hazelden Betty Ford Foundation and daughter of Betty Ford.

“He has honored my mother’s legacy and helped carry it forward in tremendous ways that will benefit many generations to come. She would be proud, and I am forever grateful.”

For the remainder of his tenure, Mishek plans to focus on diversity equity-and-inclusion efforts; a $500 million fundraising campaign; and significant expansions in virtual services and New York City outpatient services.

“Even amid the challenges of the pandemic, we are growing, innovating and diversifying,” Mishek said.

“The Hazelden Betty Ford Foundation is on a positive strategic course and is now poised for a new leader to step in, build upon our substantial foundation and usher in the next exciting era in the organization’s rich and meaningful history.”

Hazelden Betty Ford in 2019 reported revenue of $193.7 million for its 2018 fiscal year, up 5.3% from the previous year. Income, or revenue minus expenses, was $8.5 million, compared with a loss of $7.7 million in 2017.

Hazelden Betty Ford employs about 1,600.