The second daughter, Katie, had contracted polio when young and died in late 1870 when George was 15 years old. The young George left school early and started working to help support the family. As Eastman began to have success with his photography business, he vowed to repay his mother for the hardships she had endured in raising him.

In 1884, Eastman patented the first film in roll form to prove practicable; he had been tinkering at home to develop it. In 1888, he developed the Kodak camera (“Kodak” being a word Eastman created), which was the first camera designed to use roll film. He coined the advertising slogan, “You press the button, we do the rest” which quickly became popular among customers. In 1889 he first offered film stock, and by 1896 became the leading supplier of film stock internationally. He incorporated his company under the name Eastman Kodak, in 1892. As film stock became standardized, Eastman continued to lead in innovations. Refinements in colored film stock continued after his death.

George Eastman never married. He was close to his mother and to his sister and her family. He had a long platonic relationship with Josephine Dickman, a trained singer and the wife of business associate George Dickman, becoming especially close to her after the death of his mother, Maria Eastman, in 1907. He was also an avid traveler and had a passion for playing the piano.

In an era of growing trade union activities, Eastman sought to counter the union movement by devising worker benefit programs, including, in 1910, the establishment of a profit-sharing program for all employees. Considered to be a progressive leader for the times, Eastman promoted Florence McAnaney to be head of the personnel department. She was one of the first women to hold an executive position in a major U.S. company.

Eastman was associated with the Kodak company in an administrative and a business executive capacity until his death; he contributed much to the development of its notable research facilities. In 1911 he founded the Eastman Trust and Savings Bank.

In 1915, Eastman founded a bureau of municipal research in Rochester “to get things done for the community” and to serve as an “independent, non-partisan agency for keeping citizens informed.” Called the Center for Governmental Research, the agency continues to carry out that mission.

He was one of the outstanding philanthropists of his era, donating more than $100 million to various projects in Rochester; in Cambridge, Massachusetts; at two historically black colleges in the South and in several European cities. In 1918, he endowed the establishment of the Eastman School of Music at the University of Rochester, and in 1921 a school of medicine and dentistry there.

The loss of his mother, Maria, was particularly crushing to George. Almost pathologically concerned with decorum, he found himself unable for the first time to control his emotions in the presence of his friends. “When my mother died I cried all day,” he explained later. “I could not have stopped to save my life.” Due to his mother’s reluctance to accept his gifts, George Eastman could never do enough for his mother during her lifetime. He continued to honor her after her death. On September 4, 1922, he opened the Eastman Theater in Rochester, which included a chamber-music hall, Kilbourn Theater, dedicated to his mother’s memory. At the Eastman House he maintained a rose bush, using a cutting from her childhood home.

In 1925 Eastman gave up his daily management of Kodak to become treasurer. He concentrated on philanthropic activities, to which he had already donated substantial sums. For example, he donated funds to establish the Eastman Dental Dispensary in 1916. He ranked slightly behind Andrew Carnegie, John D. Rockefeller, and a few others in his philanthropy, but did not seek publicity for his activities. He concentrated on institution-building and causes that could help people’s health. From 1926 until his death, Eastman also donated $22,050 per year to the American Eugenics Society, a popular cause among many of the upper class when there were concerns about immigration and “race mixing.”

Eastman donated £200,000 in 1926 to fund a dental clinic in London, UK after being approached by the Chairman of the Royal Free Hospital, George Riddell, 1st Baron Riddell. Donations of £50,000 each had been made by Lord Riddell and the Royal Free honorary treasurer. On November 20, 1931, the UCL Eastman Dental Institute opened in a ceremony attended by Neville Chamberlain, then Minister of Health, and the American Ambassador to the UK. The clinic was incorporated into the Royal Free Hospital and was committed to providing dental care for disadvantaged children from central London. It is now a part of University College London. In 1929 he founded the George Eastman Visiting Professorship at Oxford, to be held each year by a different American scholar of the highest distinction.

Eastman suffered from depression due to his pain, reduced ability to function, and also since he had witnessed his mother’s suffering from pain. On March 14, 1932, Eastman died by suicide with a single gunshot through the heart. His suicide note read, “To my friends, my work is done – Why wait? GE.”

Eastman also funded Eastmaninstitutet, a dental care clinic for children opened in 1937 in Stockholm, Sweden.

Eastman had built a mansion at 900 East Avenue in Rochester. Here he entertained friends to dinner and held private music concerts. The University of Rochester used the mansion for various purposes for decades after his death. In 1949, it re-opened after having been adapted for use as the George Eastman House International Museum of Photography and Film. It has been designated a National Historic Landmark, and is now known as the George Eastman Museum,

At least one biographical film has been made about George Eastman. It was an independent production made in the 1940s, apparently never preserved and mostly lost to time, titled either The Life of George Eastman or George Eastman: Some Scenes Form His Life. The film, aired on television for a time into the 1960s, ends with his development of all-color negative film. In 1981, the short film The Lengthened Shadow of a Man about Eastman was made, the title of which comes from the T. S. Eliot poem 3. Sweeney Erect.