The report has formal security clearance, but it will not be released until after the December 12 election.
"Every person who votes in this country deserves to see that report before your election happens," the former US presidential candidate said.
No. 10 denies it is suppressing it.
The report by Parliament's Intelligence and Security Committee examines Russian activity in UK democracy.
It includes allegations of espionage, subversion and interference in elections.
It contains evidence from UK intelligence services such as GCHQ, MI5 and MI6 concerning covert Russian attempts to influence the outcome of the 2016 EU referendum and 2017 general election.
The report was finalised in March and referred to No. 10 on October 17.
But approval for its publication has yet to be given - and is not due to happen until after polling day.
MPs on the intelligence committee have been highly critical of that outcome, but the government has said the timing is not unusual.
Speaking to BBC Radio 4's Today programme while in the UK on a book tour, Clinton said she was "dumbfounded" that the government would not release the report.
"That should be an absolute condition," she said.
"Because there is no doubt - we know it in our country, we have seen it in Europe, we have seen it here - that Russia in particular is determined to try to shape the politics of western democracies.
"Not to our benefit, but to theirs."
She said: "I find it inexplicable that your government will not release a government report about Russian influence. Inexplicable and shameful."
Clinton said the US had a similar problem in the 2016 election, when she was defeated as the Democrat's candidate for president by Republican Donald Trump.
Trump and his campaign, she said, were under investigation for their connections with Russia, Russian agents, and others promoting Russian interests. But the American public did not know before the election.
The Russ were still "in" her country's electoral system, she said, still "pumping out propaganda".
"So there's no doubt of the role that Russia played in our 2016 election and is continuing to play.
"I would hate to see that happen here. Whatever the outcome. I don't know what's in it, (the report) any more than anybody else does.
"But certainly, people who are about to vote in a month or so deserve to know what is in a report that one has to speculate, must have something of concern, otherwise why wouldn't it be publicly disclosed?"
( With inputs from IANS )