Russia sees the UK as one of its "top targets" in the West, according to the Intelligence and Security Committee.
The ISC's long-awaited report said Russian influence in the UK was "the new normal", and accused successive governments of welcoming the country's oligarchs "with open arms".
It called for "immediate action" to help intelligence services tackle "this very capable adversary".
The committee criticised No 10 for delaying the report's publication.
Downing Street was accused of delaying its release ahead of December's UK election - which it has denied.
But speaking at a press conference to launch the report, one of the ISC's committee members, Kevan Jones, criticised the prime minister for not signing it off sooner, saying there was "no reason for delay".
The ISC's inquiry covers a number of topics, including disinformation campaigns, cyber tactics and Russian expatriates in the UK.
But much of the "highly sensitive" detail will not be published due to fears Russia could use the evidence to threaten the UK.
Source: BBC