The Metropolitan Police Service (MPS) is the territorial police force responsible for Greater London excluding the City of London (which is the responsibility of the City of London Police). It is commonly referred to as the Metropolitan Police and informally as "the Met" or sometimes MP; in statutes it is usually described in lower case as the "metropolitan police" without the appendage "Service".

With over 31,000 Police Officers, 1,070 Special Constables, 13,661 police staff, 414 traffic wardens and 2,106 Police Community Support Officers (PCSOs) the MPS is the largest force in the United Kingdom. The headquarters is at New Scotland Yard in Westminster, commonly known as Scotland Yard, although administrative functions are increasingly based at the Empress State Building (ESB) and by the end of 2007 all command and control functions will be transferred to the three Metcall complexes. Its head is the Commissioner of Police of the Metropolis or simply the Commissioner, responsible to the Metropolitan Police Authority. The post was first held jointly by Colonel Sir Charles Rowan and Sir Richard Mayne. The current Commissioner is Sir Ian Blair QPM.