Born in 1885 in Okinohata Village, Yamato District, Fukuoka (today Yanagawa, Fukuoka), as the eldest son of Kitahara Chotaro, a wealthy merchant of the sake-brewing trade. His given name was Ryukichi. Yanagawa, with waterways winding through the town, is known as a 'water village' and became the original landscape of Hakushu's verse. He devoted himself to literature in his Denshukan Middle School days and went up to Tokyo in 1904 to enter the Waseda University English preparatory course. In 1906 he joined Yosano Tekkan's Shinshisha and contributed poems to 'Myojo.' In 1908 he formed the 'Pan no Kai' with Kinoshita Mokutaro, Yoshii Isamu, Ishii Hakutei and others, advancing the new Romantic literary movement. He published his first poetry collection 'Jashumon' in 1909 and his second 'Omoide' in 1911, securing a solid place in the poetry world. In 1912 his affair with the married Matsushita Toshiko was discovered and he was imprisoned on a charge of adultery (later released by reconciliation); he married Toshiko in 1913 but divorced in 1914. From 1916 he moved between the Ogasawara Islands, Miura Misaki, and Odawara, devoting himself to writing. From 1918 he contributed poems to the children's literary magazine 'Akai Tori' (Red Bird) edited by Suzuki Miekichi and began his career as a writer of children's songs. He produced many masterpiece children's songs sung to this day to compositions by Yamada Kosaku, Narita Tamezo, and Nakayama Shinpei — 'Karatachi no Hana,' 'Kono Michi,' 'Machibouke,' 'Pechika,' 'Ame Furi,' 'Sunayama,' 'Yurikago no Uta,' and more. In tanka too he opened his own ground with 'Kiri no Hana' (1913) and 'Kurobi' (1942). In 1937 he developed eye disease from kidney trouble due to diabetes, and by 1939 was nearly blind. He died at his home in Asagaya, Tokyo, on November 2, 1942, aged 57.

Rich in sensibility and with an outstanding sense of color, he had a delicate poetic heart that mobilized all five senses — sight, touch, smell, and more. At the same time he led a turbulent life — the adultery affair, three marriages, the wandering habit of constantly changing his surroundings for the sake of his work. A rare multi-poet who moved freely between children's songs, folk songs, tanka, poetry, symbolist verse, and free verse.

The greatest writer of modern Japanese poetry and children's songs. His children's songs — 'Karatachi no Hana,' 'Kono Michi,' 'Pechika,' 'Ame Furi' — are still sung in school education and loved across generations. In tanka too he established his own style with 'Kiri no Hana' and 'Suzume no Tamago,' breathing new wind into modern tanka. Sites connected to him remain in many places: the Kitahara Hakushu birthplace and memorial in Yanagawa, Fukuoka; the Hakushu Children's Song Museum (his former home) in Odawara, Kanagawa; and the Hakushu poetry monument in Karuizawa, Nagano. With Miki Rofu, he created the golden age of modern poetry called the 'Haku-Ro era.'