In 1856 the Governor-General promulgated an Act treating Calcutta Police as a separate organisation and S. Wauchope, who was then the chief magistrate of Calcutta, was appointed as the first commissioner of police. He had to face difficult days because of the Sepoy Mutiny of 1857, the first upsurge against British rule. He handled the situation ably and was knighted for his achievement. During the incumbency of his successor V.H. Schalch the Calcutta Police Act and the Calcutta Suburban Police Act, which are still in force, were enacted in 1866. Two years earlier (1864) the Commissioner of Police had become the Chairman of the Justices as well and a Deputy Commissioner was appointed to look after the executive police.

It was Sir Stuart Hogg who first set up the Detective Department in Calcutta Police in November 1868 with A. Younan as the superintendent and R. Lamb as the first-class inspector. Hogg was both the commissioner of police and the chairman of the Calcutta Municipal Corporation. His name is still remembered in the Hogg Market, more popularly known as the New Market, one of the landmarks of the city of Kolkata. Sir Fredrick Halliday, who was appointed as the commissioner of police in 1906, also introduced several changes in the administration of Calcutta Police including the system of running a Control Room. His biggest achievement was the creation of the Special Branch in June 1909. For his numerous contributions to the growth of the city police, he may rightly be called the father of modern Calcutta Police. During his tenure Calcutta Police was divided into three town divisions and two suburban divisions.

Another person who deserves mention is Sir Charles Augustus Tegart, who headed the Detective Department and virtually controlled the Special Branch since his joining Calcutta Police in 1902. He was the first officer of the Indian Police (IP) in the organisation and on his report the Special Branch was created. He reorganized the city police force and made it efficient. A highly decorated officer, he was the Commissioner of Police in the years 1923-31 and was admired for keeping the city free from crime. However, he was unpopular with freedom fighters and his encounters with revolutionaries are a part of popular Bengali folklore.