WASHINGTON — Ward B. Chamberlin Jr., a public broadcasting pioneer who led major stations in New York and Washington and played a critical role in kick-starting the career of documentary filmmaker Ken Burns, died Feb. 23 at a retirement community in Bedford, Mass. He was 95.

The cause was complications from dementia, said a daughter, Carolyn. He was a resident of Westport, Mass.

An Ivy League-educated corporate lawyer, Mr. Chamberlin was in his late 40s when he swerved by chance into a career as a media executive. He had spent years as the right-hand man in executive suites to Frank Pace Jr., a former US budget director and Democratic Party stalwart.

In 1968, President Lyndon B. Johnson named Pace board chairman of the nascent Corporation for Public Broadcasting. He knew nothing of the medium of television, so he tapped Mr. Chamberlin, who was also his squash and backgammon partner, to investigate.

Mr. Chamberlin spoke with a friend in the industry and reported back, according to a Princeton alumni publication, ‘‘Frank, you’d better take this job or we’re not going to be friends. This is going to be a lot of fun.’’

It was also a lot of work, but over the next several years, Mr. Chamberlin was given free rein to take an enormous and ill-defined mandate and shape it into a concrete reality. As Pace’s deputy, he had the authority and the organizational skills to arrange the Corporation for Public Broadcasting’s budgetary, personnel, and programming distribution structure.

He said his most important endeavor was persuading all the station heads — from the most powerful to the smallest — to agree to a decentralized structure in which each licensee had autonomy.

Over the next several years, he served as executive vice president of public broadcasting’s WNET in New York and senior vice president of the Public Broadcasting Service. In 1975, he became president and chief executive of WETA, the struggling Washington-area public radio and television station.

Sharon Percy Rockefeller, his successor, said WETA was a ‘‘tiny afterthought’’ in the constellation of public broadcasting at the time, approaching bankruptcy, suffering from weak leadership and organization, and offering scant original programming despite its prime location in a world capital.

Over the next 14 years, Rockefeller said in an interview, Mr. Chamberlin ‘‘took us from that fragility to a position of strength,’’ making WETA the third-largest producer of original shows for PBS, behind WNET and WGBH in Boston. Its operating budget rose to $28 million from about $6 million during his tenure. (WETA is now the No. 2 producer, after WGBH, and its budget is $96 million, according to Rockefeller.)

The station produced under Mr. Chamberlin’s watch some of the nation’s best-known public affairs fare, including ‘‘The MacNeil/Lehrer Report’’ (now ‘‘The NewsHour’’) and ‘‘Washington Week in Review’’ (now ‘‘Washington Week’’). WETA also produced entertainment programs such as ‘‘In Performance at the White House,’’ ‘‘The Kennedy Center Presents’’ and ‘‘A Capitol Fourth.’’

In an interview Friday, Burns said he first approached Mr. Chamberlin in 1985, before the filmmaker was widely known. Burns said he needed $50,000 to complete his feature-length documentary about Huey Long, the fiery Louisiana governor and US senator who was assassinated in 1935.

He had heard Mr. Chamberlin was a history buff and took a chance on showing him a rough cut. ‘‘I immediately recognized that this was a really talented man,’’ Mr. Chamberlin later said, explaining why he had WETA take the unusual step of covering the cost of finishing the film.

Mr. Chamberlin remained an ardent champion of Burns’s works, with WETA coproducing many of his subsequent documentaries.

Perhaps most notable was ‘‘The Civil War’’ (1990), which was initially projected to run five hours but more than doubled in the editing room. Furthermore, it was to rely heavily on still photographs over action sequences — hardly a promising way to engage the attention of viewers for one hour, much less 12.

‘‘The Civil War’’ had already proved a hard sell with underwriters. Burns said he bought Mr. Chamberlin dinner and, once they were both fortified with stiff drinks, spilled the news that the documentary’s run time was a half-day.

‘‘All he said was, ‘Is it good?’ ‘‘ Burns said. ‘‘He stood by me . . . when no one else would.’’

‘‘The Civil War,’’ which drew critical superlatives and a shelf of awards, became one of the most-watched series ever to air on public television.

Ward Bryan Chamberlin III was born in New York City and grew up in South Norwalk, Conn. He lost his right eye to meningitis as a child but excelled in sports, becoming an all-American soccer player and captain at Princeton University.

Exempt from military service because of his missing eye, he left college in 1942 — a year before his scheduled graduation — following a classmate into the American Field Service relief organization during World War II.

He became a volunteer ambulance driver, serving on the front lines during the Battle of Monte Cassino in Italy.

Mr. Chamberlin completed his Princeton degree in 1946, graduating summa cum laude from the Woodrow Wilson School of Public and International Affairs. After graduating two years later from Columbia Law School, he joined his father’s corporate law firm. He also worked for the post-World War II economic aid program called the Marshall Plan.

In 1955, he joined the legal department of the military contracting giant General Dynamics, working under Pace there and later at the International Executive Service Corps before they went to the Corporation for Public Broadcasting.

Within a few years of leaving WETA, Mr. Chamberlin was recruited to WNET in New York to revive the financially flailing station. As station vice president, he helped undertake a fund-raising campaign and poured money from newly flush coffers into vibrant original programming.

His first marriage, to journalist Anne Nevin, ended in divorce. His second wife, the former Lydia Gifford, died in 2009 after 58 years of marriage. He leaves two daughters from his second marriage, Carolyn of New Haven and Margot of Newton, Mass; and four grandchildren.