Joseph E. Robert Jr., 59, who rose from a troubled childhood to become one of Washington’s wealthiest financiers and most generous philanthropists, known for his raucous annual Fight Night boxing event that raised millions of dollars for children’s charities, died Dec. 7 at his home in McLean. He had a glioblastoma, a form of brain cancer.

Mr. Robert’s death was confirmed by Mike McGillis, managing director of JER Partners, the real estate company Mr. Robert founded in 1981.

Through bravado and persistence, Mr. Robert asserted his place in Washington’s business firmament from an unlikely starting place. He had barely muddled through high school and was kicked out of college for fighting, rendering him homeless for more than a month. After working as a bouncer, selling encyclopedias and unloading trucks, he had an epiphany.

Convinced that he was throwing away his life, Mr. Robert decided to go into the real estate business and focus on distressed assets. He bought handfuls of real estate books and started purchasing condos in Beltsville when he was 20. In 1981, he launched his asset-management company, despite having been told that it was an unwise venture during a recession. He went to nearly 20 Washington area banks seeking a $500,000 loan.

Riggs National Bank finally agreed to give him the money after Mr. Robert assured the loan officer that he was “going to be the biggest real estate workout guy in town.”

He was right. In one of his most publicized deals, his J.E. Robert Cos. in 1990 won a government contract worth $41 million over three years to sell a grab bag of strip malls, apartment complexes and other assets worth billions of dollars held by failed savings and loan associations in Texas. The deal was part of an unprecedented effort by the Resolution Trust Corp., which oversaw the enormous S&L bailout, to recruit private asset-management companies.

By the 1990s, Mr. Robert had offices and properties around the world and at one point estimated his wealth at about $1 billion. Even when he went skiing, business came first. To keep up with business deals taking place in different time zones, he had a ski helmet equipped with a cellphone.

He had homes from Potomac to Colorado and a list of friends that included Oprah Winfrey, the rock star Bono, Middle East sheiks and Russian oligarchs. He squired glamorous women across the Mediterranean, survived a helicopter explosion near the North Pole and explored the Colombian jungle in search of guerrilla fighters.

Mr. Robert’s most prized possession: a piece of string from the garment of a Colombian tribal chief. He wore it tied around his wrist. Receiving the string “was one of the most remarkable experiences of my life,” Mr. Robert told Washington Business Journal. “I gave him the Gucci sunglasses I was wearing.”

After he made a huge fortune performing complicated financial transactions during the S&L crisis, Mr. Robert became one of the softest touches­ in town, raising and giving bushels of money for his two philanthropic devotions: children’s education and children’s health care.

The annual Fight Night at the Washington Hilton, a stag smoker featuring hostesses in slinky gowns and a high-amp performance by the Washington Redskins’ cheerleaders, has raised $50 million for children’s charities since 1990.

Mr. Robert directed tens of millions of his own dollars to children’s charities and also put the arm on others to give. In September 2009, after four years of effort, Mr. Robert’s Middle East connections allowed him to broker a deal with the royal family of Abu Dhabi that brought $150 million to Children’s National Medical Center.

Mr. Robert helped raise almost $1 billion for children and education in the Washington area and elsewhere. In 2000, he donated $25 million to Children’s Hospital for a new surgical center. He was chairman of the Washington Scholarship Fund, which raised money to send underprivileged children to private schools.

He served on the boards of the National Symphony Orchestra and the Kennedy Center because he wanted more inner-city children to be exposed to the arts.

His passion for Children’s Hospital began when he slept on the floor of one of its rooms when his son, Joseph III, was having surgery on his rib cage. Mr. Robert would eventually serve as chairman for a hospital campaign that raised $200 million.

Later, Mr. Robert flew to Iraq, where his son was serving in the Marines. At Camp Pendleton in San Diego, he helped organize a concert featuring pop stars Destiny’s Child, Kiss, Godsmack and Ted Nugent.

Joseph Edgar Robert Jr. was born Feb. 24, 1952, in Takoma Park and raised in Silver Spring. His father worked in real estate, and the family was often in debt.

“We never had any money,” Mr. Robert recalled in a 2007 interview. “I was always working. I had a paper route and worked at a restaurant.”

Mr. Robert once told The Washington Post that his father was an “alcoholic abuser.” His father left home when Mr. Robert was in grammar school, and the two didn’t communicate for many years.

He showed a penchant for business early on. At 10, he recovered some discarded boxing equipment and organized matches for neighborhood kids in his back yard on Rockdale Drive. He stuck broom handles in the ground and with clothesline made a boxing ring. He charged for popcorn and lemonade.

He sold applesauce. He sold Christmas trees. He sold bacon.

He was in the fourth grade.

“They were the fight nights of the ’50s and ’60s,” he recalled.

Mr. Robert attended St. John’s College High School in Washington, where he famously got into fistfights, set off a smoke bomb and was expelled on more than one occasion. He also excelled in math and chemistry.

His father went to a loan shark in Philadelphia to get money for tuition. “I never got to pay my tuition on time, so I almost never got my report card. The good news is I didn’t get my report card,” Mr. Robert said.

The teenager grew at St. John’s, where the competition was as ferocious in the classroom as it was on the playing field.

“There was a real focus on winning,” he recalled in an interview a few years ago. “It wasn’t just sports. It was grades. It was class rank.”

One semester, Mr. Robert would have a 70 average; the next, he would get a 96 average with honors.

He developed a lifelong affection for the school, becoming one of its biggest benefactors. He gave $1 million for a Joseph E. Robert Jr. science hall. He also paid for children of family and friends to attend St. John’s, from which he graduated in 1970.

Mr. Robert said he was expelled from Mount St. Mary’s College in Emmitsburg, Md., after a violent confrontation with a fellow student who was abusing a dog.

“I told him the next time he slapped the dog, I would slap him,” he told The Post in 2009.

When he heard the student beating the dog, Mr. Robert broke his way into the room with a baseball bat. He rescued the dog and kept it as a pet for 17 years.

Mr. Robert’s marriages to Gayle Davis and Jill Sorensen ended in divorce.

Survivors include one son from his first marriage, Joseph E. Robert III of McLean, and one from his second, Luke S. Robert; his father, Joseph E. Robert Sr. of Ocean Pines, Md.; his mother, Aimee Lou Robert of Silver Spring; three sisters, Janice E. Robert of Gaithersburg, Christine E. Robert of New York and Cynthia L. Robert-Clark of Miami; and one brother, Thomas P. Robert of Sebring, Fla.

Two years ago, after his brain cancer diagnosis, he told The Post that God should do a “net present value” on his life.

“I believe the numbers will convince him I am more valuable doing his work here!” he said.