[1] He previously served as President & CEO of The Education Trust, a national civil rights nonprofit which seeks to identify and close opportunity and achievement gaps for students from preschool through college.

When later describing the importance of education, King credits one of his New York City public school teachers with saving him from being "shot or in prison" following the trauma caused by his parents' deaths.

[14] He moved in with his uncle, a Tuskegee Airman, in Cherry Hill, New Jersey, where he applied and was accepted to Harvard University.

[26] Through Race to the Top funding, network teams were launched in every region of the state and in every large district to provide training and embedded support to educators around implementation of the Common Core and the resources on EngageNY.

[27][28] In 2013, New York became one of the first states in the country to administer exams that measure whether students are meeting Common Core standards.

[29] To support this work, Commissioner King championed the creation of the Strengthening Teacher and Leader Effectiveness (STLE) grants program that funded school districts in utilizing a comprehensive approach to recruitment, development, support, retention and equitable distribution of effective teachers and school leaders.

[32] In April 2014, amidst the national Common Core controversy, the state teachers' union called for his resignation.

[33] In one of his last efforts as State Education Commissioner, King piloted a program in New York city to increase socioeconomic diversity among schools through integration.

[39] Even if their education reform agendas are similar, Duncan pointed out that King's background (he has African-American and Puerto Rican heritage, and was orphaned at age 12) gave him a "set of experiences that I think will help to make him especially impactful.

Fortunately ... we also have a great replacement for Arne in Dr. John King, who is going to be doing outstanding work helping to implement this [new legislation].

[43] In September 2016, King travelled to six states to discuss education—visiting 11 cities and towns—for the Obama administration's final Back to School Bus tour.

[43] King worked to advance the implementation of the Every Student Succeeds Act (ESSA), saying that it provides for a "well-rounded education" and that he is "among those who worry that the balance has shifted too much away from subjects outside of math and English that could be the spark to a child's interest and excitement, and are actually essential to success in reading, and are critical to a child's future.

"[44][45] In November 2016, the U.S. Department of Education released the final ESSA accountability rules, boosting state flexibility in key areas.

[46] King continued his efforts towards socioeconomic and racial integration by centering federal education policy on increasing student diversity and in December 2016 he announced a $12 million grant competition "that would give up to 20 school districts the opportunity to craft new roadmaps for increasing student diversity and get started on those plans.

"[65] The organization's areas of policy focus include investing in public education, strengthening the social safety net, broad-based economic development benefiting historically marginalized communities, and climate change and environmental justice.

[68] In January 2022, he announced Michelle Siri, the executive director of the Women's Law Center of Maryland, as his running mate for Lieutenant Governor.

[69] His platform included funding and implementing the Blueprint for Maryland's Future,[70] achieving net-zero carbon emissions by 2035,[71] and accelerating the state's transition to a minimum wage of $15 an hour.

[79] On July 19, 2022, King lost the primary, placing sixth behind Doug Gansler, Peter Franchot, Tom Perez, and Wes Moore.

[citation needed] King co-chairs This Is Planet Ed with former New Jersey Governor and EPA Administrator Christine Todd Whitman, an initiative of the Energy and Environment Program of the Aspen Institute which seeks to mobilize the education sector to act on climate.

King's grandmother was among the earliest graduates of the University of Maryland Eastern Shore in 1894, a historically Black college which was then known as Princess Anne Academy.