The bill, which was published online Tuesday, gives former presidents and their families immunity from prosecution for crimes committed during their lifetime.
They will also be exempt from questioning by police or investigators, as well as searches or arrests.
The legislation was part of constitutional amendments that were approved this summer in a nationwide vote that allow Putin, 68, to remain president until 2036.
Prior to the bill becoming law, former presidents were immune from prosecution only for crimes committed while in office.
Now a former president can still be stripped of immunity if accused of treason or other grave crimes and the charges are confirmed by the Supreme and Constitutional courts.
But the legislation Putin signed on Tuesday will additionally grant former presidents a lifetime seat in the Federation Council or senate, a position that assures immunity from prosecution upon leaving the presidency.