Sonnenberg was born in Brest-Litovsk, Russia, now part of Belarus. He began his life living in poverty in a small wooden hut. Because of this poverty, his family emigrated to the United States with his family in 1910 to Lower East Side, Manhattan, New York City. Sonnenberg attended Public School No.62 and then DeWitt Clinton High School. He took part in drama and dance at Henry Street Settlement, where his mother was a cleaning lady. Miss Wald, the director, was very impressed with Ben. At the age of 16, she offered him a job as the leader of the boy's club, and in turn allowed him to continue his schooling and live at the settlement house. Two years later, Miss Wald helped him get a scholarship to study at Columbia College. He got a job covering Columbia University sports for the Brooklyn Eagle. This helped his writing skills to become a publicist.
He married Hilda Kaplan in March 1924. Brendan Gill, a close friend of Sonnenberg claimed, "Ben wanted to be remembered as he was in his prime." His will was written on December 7, 1977 after he learned he was terminally ill with throat cancer. The will directed his executors of this estate to destroy all his files and papers. On September 5, 1978 Sonnenberg died in New York City at age 77 of a heart attack on September 6, 1978.
Sonnenberg was unsatisfied by the challenge of college and answered an ad in The New York Times with the Chicago Portrait Company as a door-to-door salesman. He became bored and quit after two months. Then, he hitchhiked to Flint, Michigan where he worked as a reporter and movie critic for the Flint Journal. He returned to New York City in 1921.
Upon returning to New York City, his first work in the public relations field was writing stories for the American Jewish Joint Distribution Committee. In 1922, Miss Wald got a call from Lewis Strauss, the former secretary to Herbert Hoover and director of the American Relief Administration with the task to get food and medical assistance to the famine-stricken areas of Russia and Europe. Sonnenberg took the job where he realized what it was like to be rich, and he fell in love with the lifestyle that coincided. At the age of 22, he rented a room in Greenwich Village and made an earning by providing publicity for Jewish fund drives, writing stories for the American Jewish Joint Distribution Committee. He also did some public relations work for the Salvation Army, and a few night clubs.
A self-described "cabinetmaker who fashioned large pedestals for small statues", Sonnenberg represented many clients. While his company, Publicity Consultants Inc., was nominally located in offices on Park Avenue, his real business was done in his five-story townhouse in the Gramercy Park neighborhood of Manhattan, where he was renowned for his lavish entertaining for his clients and his contacts in the press. As his son would later describe in his memoir Lost Property: Memoirs and Confessions of a Bad Boy, "our home, my home, was a stage for his work".