His father, Qazi Muhammad Kazem, served as a Ṣadr Amīn (revenue judicial officer) for the Company Raj.

[1] Sirajul Islam began his career as the assistant headmaster of the Pogose School.

He became the assistant secretary of the Central National Muhamedan Association in 1885 and was made an honorary member of the Bengal Provincial Educational Conference.

[1] Sirajul Islam was a supporter of Begum Rokeya and her campaign for the education of Muslim women.

[6] He had initially opposed the 1905 Partition of Bengal and the establishment of the University of Dacca, but later changed his mind regarding both matters.