BOSTON — Marylou Sudders, a former state mental health commissioner and chief executive of the Massachusetts Society for the Prevention of Cruelty to Children, was tapped Friday by Gov.-elect Charlie Baker to serve as secretary of Health and Human Services in his administration.

Sudders, currently an associate professor at Boston College’s School of Social Work, will oversee one of the largest and most sensitive segments of state government.

“She will bring leadership, passion, firsthand operational knowledge, broad experience, and a collaborative spirit to this most challenging task,” Baker said in a statement announcing his latest Cabinet pick. The governor-elect said he’d known Sudders for more than 20 years and the two worked together under Republican Gov. Paul Cellucci in the 1990s.

According to Massachusetts’ “Open Checkbook” website, which lets residents find out how their tax dollars are being spent, Health and Human Services accounted for $16.3 billion, or about 40 percent of total annual state spending, making it the single most expensive area of state government. High-profile agencies under the HHS umbrella include the Department of Children and Families and the Department of Public Health.

DCF came under intense scrutiny after social workers lost track of 5-year-old Jeremiah Oliver, whose family had been under the agency’s watch. The boy’s remains were later found along a state highway. Baker and his Democratic opponent, Attorney General Martha Coakley, sparred during the recent gubernatorial campaign over their respective records on child welfare issues.

Coakley issued a statement Friday praising Baker’s appointment of Sudders.

The public health agency has been criticized for its bumpy rollout of the state’s medical marijuana program. No marijuana dispensaries have opened yet in Massachusetts, more than two years after voters approved the measure, and Baker has suggested the licensing process may need to be restarted.

As mental health commissioner, Sudders oversaw an agency that served nearly 25,000 adults with mental illness, as well as emotionally disturbed children, according to the statement.

In 2003, she became president and CEO of Massachusetts Society for the Prevention of Cruelty to Children, a nonprofit organization with 25 offices and 800 staffers around the state.

House Speaker Robert DeLeo named her to an advisory panel that made recommendations leading up to passage of a landmark gun safety bill earlier this year.

“Having dedicated my professional life to social work, mental health and caring for the most vulnerable members of our society, I am humbled and inspired to take on this role,” Sudders said of her new post.

Susan Tousignant, president of SEIU Local 509, said the union of 17,000 human services workers applauded the choice.