Umar Khan was declared the ruler after the death of his elder brother Alim Khan in 1809. Umarkhan continued the policy of his brother Alim Khan to expand the Kokand Khanate, but he used softer methods.

In 1815, he conquered the city of Turkestan from the Emir of Bukhara Haidar. He visited the tomb of Khoja Ahmed Yasawi, sacrificing 70 rams and gifting all the sheikhs of this famous shrine. Here he announced that he would not just be called a khan, but would take the title of amir al-muslimin (commander of the faithful). The title was proclaimed during Friday prayers.