Donald Trump and his aides did not collude with Russia in the 2016 election campaign, special counsel Robert Mueller concluded in his report, according to a summary from the US Attorney General.
Mr Mueller also did not find that Mr Trump obstructed justice in his alleged attempts to thwart the investigation, instead choosing not to reach a conclusion and simply presenting the evidence.
The US attorney general and his deputy - two Trump appointees - then decided there was not enough proof to charge the US president with obstruction of justice.
Mr Mueller also decided to recommend no further indictments and has no sealed indictments waiting to be made public, meaning he will not bring any more charges now his probe is complete.
The findings amount to a major victory for Mr Trump after 22 months of Mr Mueller's investigation and triggered celebration from the White House and leading Republicans.
In his first reaction Mr Trump said: "It's complete exoneration. No collusion, no obstruction."
The president said it was "a shame" that the country and his presidency had to go through the investigation and called it an "illegal take down that failed".
Mr Trump also appeared to call for an investigation into the Mueller probe itself and how it began.
Sarah Sanders, the White House press secretary, said: "The findings of the Department of Justice are a total and complete exoneration of the President of the United States."
Lindsey Graham, the Republican senator close to Mr Trump, tweeted: "Good day for the rule of law. Great day for President Trump and his team.
"No collusion and no obstruction. The cloud hanging over President Trump has been removed by this report."
However Democrats are demanding that Mr Mueller's full confidential report be published and that all the underlying documents be handed to Congress so they can be reviewed.
The topline findings from Mr Mueller's report were contained in a four-page summary written by William Barr, the US attorney general.
The summary was submitted to senior congressmen and released to the public on Sunday afternoon, giving the first insight into what Mr Mueller had concluded.
In the summary, Mr Mueller is quoted saying: "[T]he investigation did not establish that members of the Trump Campaign conspired or coordinated with the Russian government in its election interference activities."
Elsewhere Mr Mueller is quoted saying: "The evidence does not establish that the President was involved in an underlying crime related to Russian election interference".
That finding was effectively victory for the US president, who has been saying constantly during the two years since he entered the White House that there had been "no collusion".
As well as clearing Mr Trump and his campaign of conspiring with the Kremlin, Mr Mueller's report also dealt with the allegations that the US president had obstructed justice by hampering the investigation.
Mr Mueller did not reach a decision on whether Mr Trump had obstructed justice - meaning it was not a total victory for the president - instead deciding not to come to a conclusion.
Mr Barr's summary cites Mr Mueller referencing "difficult issues" of law and fact - a likely nod to Department of Justice guidelines that say a sitting president cannot be indicted.
The summary of the report quotes Mr Mueller saying of obstruction of justice: "While this report does not conclude that the President committed a crime, it also does not exonerate him".
Given Mr Mueller decided not to make a decision on obstruction of justice but instead just hand over evidence, the Justice Department's leaders was left to made a determination.
Mr Barr and Rod Rosenstein, the deputy attorney general, decided there was not enough evidence to conclude that Mr Trump had acted with "corrupt intent", and therefore decided he had not obstructed justice.