The Baltimore-based group said that its rosters of online activists and donors have grown tremendously during his five-year tenure. Jealous was the group's youngest-ever leader when he was hired as its president at age 35 in 2008.
In a written statement Sunday, Jealous, now 40, said he plans to pursue teaching at a university and wants to spend time with his young family.
"The NAACP has always been the largest civil rights organization in the streets, and today it is also the largest civil rights organization online, on mobile and at the ballot box too," Jealous said. "I am proud to leave the association financially sound, sustainable, focused, and more powerful than ever."
Jealous plans to step down on Dec. 31. His departure plans were first reported by USA Today.
Jealous told the newspaper he also plans to start a political action committee to raise money to elect diverse progressive candidates to public office, though not necessarily only Democrats. During President Barack Obama's first campaign, Jealous said he teamed with others to create a fundraising group that raised $10 million to help elect the first black president.
Jealous is credited with improving the NAACP's finances and donor base over the past five years. The group said its donors have increased from 16,000 people giving each year to more than 132,000.
During his tenure, the NAACP also has embraced gay marriage rights in a historic vote to endorse same-sex marriage in May 2012. "Civil marriage is a civil right and a matter of civil law," the group said, citing the 14th Amendment's equal protection clause.
Jealous told The Associated Press recently that a broader coalition is needed to fight the civil rights battles of the 21st century.
"Last century we needed lawyers; this century we need big, broad coalitions," he said. "When extremists decide to attack all our communities, they must hope that there will be infighting. But we have stood all for one and one for all. That is how we will win."
An NAACP spokesman said Jealous was not available for an interview until a formal announcement on Monday.
Jealous began his career as a community organizer in Harlem with the NAACP Legal Defense Fund. He was suspended from Columbia University in New York City after organizing student protests and went on to work as a reporter for the Jackson Advocate newspaper in Mississippi.
Jealous has led the NAACP to advocate against "stop-and-frisk" police tactics and stand-your-ground laws following the death of Florida teenager Trayvon Martin. He has also fought to abolish the death penalty at the state level.
NAACP Chairman Roslyn Brock accepted Jealous' resignation in the past week. She said the group would continue its fight to restore part of the Voting Rights Act that was recently struck down by the Supreme Court, as well as work to boost its civic engagement efforts and ensure that black Americans are able to obtain health insurance under the nation's health care overhaul.
Brock thanked Jealous for his service.
"Under his leadership, the NAACP has built a highly competent staff that will carry our mission forward and meet the civil rights challenges of the 21st century," she said. "Our board, staff and volunteer leaders throughout the country deeply appreciate his sacrifice and will continue to implement our game-changing goals for the next half century."