However, in 1860, her mother Sikandar Begum was recognised by the British as ruler of Bhopal in her own right, making the young Shah Jahan the sovereign heiress.

During her reign, Shah Jahan reformed the provincial tax system, improved labour and army revenues, modernised the military, built dams and artificial lakes, reformed and rebuilt the state's police force and stabilised Bhopal in the aftermath of two plagues, when the population had dropped to 744,000.

She began the construction one of the largest mosques in India, the Taj-ul-Masajid and built the Taj Mahal palace at Bhopal.

In 1918 she wrote the Iffat-ul-Muslimaat, where she describes the notions of purdah ad hijab in customs in Europe, Asia, and Egypt.

In 1855, Shahjahan Begum married below her rank to Baqi Muhammad Khan, a nobleman of minor status in Bhopal, as his third wife.

[5] In 1901, she was afflicted with cancer of the mouth; shortly thereafter, a message was published for the people of Bhopal asking forgiveness if Shahjahan had wronged any of her subjects, causing public grief over the illness of a popular ruler.