Scotland Yard Commissioner Bernard Hogan-Howe said body art that can be seen by the public "damages the professional image" of the service.
He also ordered a "tattoo amnesty" in which anyone who already has marks on their hands, neck or face must declare them within weeks or be sacked, the Daily Mail reported.
The ban comes amid increasing concern among senior ranks nationwide over complaints from crime victims that some young officers appear "thuggish".
They are particularly worried about the trend for tattoo "sleeves" in which wrap-around tattoos are inked along the arm.
But rank-and-file representatives claim associating tattoos with criminals is old-fashioned and police should reflect the public they serve.
Hogan-Howe announced the tattoo diktat in a message to all 52,000 officers and staff yesterday.
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"All visible tattoos damage the professional image of the Metropolitan Police Service. This corporate announcement discusses a specific requirement from the Met dress code policy in relation to the display of tattoos," he said.
"With effect from the date of this announcement, tattoos on the face, or visible above a collar line, or on the hands are not permitted. All other tattoos must be covered," Hogan-Howe added.
"The Met is aware that some officers and staff already have prohibited visible tattoos. These are defined as tattoos that cannot be covered by everyday clothing," Hogan-Howe said.
"It will be a requirement, by the Commissioner, that all officers and police staff with existing tattoos defined as 'visible' must register such tattoos as a formal written declaration to their line manager before November 12," he said.
"Any officer or member of police staff who fails, without reasonable excuse, to declare and register an existing visible tattoo will be liable to disciplinary action. Such a failure is liable to be considered to be gross misconduct," he added.
Police officers are banned from having offensive tattoos, including ones with discriminatory, violent or intimidating slogans.