The Metropolitan Police received £22.7 million-worth of gifts and donations including cars, bikes and tickets to various events over five years, the force has revealed.
Gifts such as football shirts, tickets to matches and gigs, and cars made by Land Rover, BMW and Jaguar were all donated to Scotland Yard during the five years from 2007.
Figures released after a freedom of information request by the BBC detailed hundreds of donations made to units across the capital.
A Metropolitan Police spokesman said all donations were regulated by the Mayor's Office for Police and Crime (MOPAC), and that anything more than £50,000 must be referred to the Deputy Mayor for Policing and Crime for approval.
He said: "The MPS has a long history of working with a variety of partners to tackle different types of crime. Funding from organisations outside the MPS is used in several areas of police activity such as the Dedicated Cheque and Plastic Crime Unit. This is fully funded by the banking industry through UK Payments.
"Such arrangements are subject to rigorous parameters. They do not make any of the statutory functions of the MPS dependent on this funding nor does it allow for any companies to interfere with the duties of the police. In these arrangements, funding for the larger and more operational activities is usually provided by an industry body or a group of companies."
London Assembly member Jenny Jones said she was concerned about some of the donations on the list, such as the Association for Payment Clearing Services funding a fraud unit.
She said: "I am worried about some of the major entries included in this list, such as British Oil Security Syndicate, which funded a police officer who was dedicated to reducing criminal activities at petrol stations.
"We need to think carefully about allowing rich companies to fund Met Police operations. We have to ask, is the Met doing what they are paid to do by outside agencies, or what the public expects them to do? There is a 'buy-a-cop' feel to this that looks suspiciously like privatisation.
"We have to have a police force that is not only impartial, but also seen to be impartial. Rich companies cannot be allowed to buy a special level of policing above what the public receives."