His father was also a famous children's story writer Upendra Kishore Ray. He was the convenor of "Monday Club" which was a weekly gathering of likeminded people at the Ray residence. He was born in a Brahmo family on 30 October 1887. He studied the technology of block making thereby setting up a business of making quality blocks. He graduated in Physics from Presidency College. He is also known as a great illustrator. He had also developed new methods of halftone block making. He also learnt printing technology. He ran the publishing businesses and the Sandesh magazine for eight years. He was married to Suprabha Das.
He grew up in an environment that promoted his literary skills. His father was a multi faceted personality as he was a talented writer, painter and illustrator; musician and composer; a pioneering technologist and hobbyist astronomer. He had designed sliding calculator to help in setting up the camera during process work. He was very close to Rabindranath Tagore, who had great influence on Sukumar. Sukumar and his younger brother Subinay were involved in the firm M/s U. Ray & Sons. He was a leader of the reformist wing in the Brahmo Samaj. Sukumar Ray wrote a poem "Atiter Katha" that presented the history of the Brahmo Samaj.
He died in 1923 of severe infectious fever, "Leishmaniasis". His works are: Abol tabol, Pagla Dashu, Khai-Khai, Heshoram Hushiyarer Diary, HaJaBaRaLa, Jhalapala O Onanyo Natok, Lakkhaner Shoktishel, Chalachittachanchari, Shabdakalpadrum and Bohurupee. He wrote "Halftone Facts Summarized" that was published in the Penrose Annual (1912).
He had received Award of Merit by 'Boy's Own Paper' for excellence in photography in November 1904. He also wrote "Standardizing the Original" that was published in the Penrose Annual (1913-'14). He had also penned an article on the Pin-hole theory published in July, 1913 issue of The British Journal of Photography. He possessed a swift mind and synthesized words and images very well. He still remains the favourite poet of children in Bengal.