Hunter Biden's lucrative work at a Ukrainian energy firm while his father was vice-president was "problematic", a report by Republican senators says.
But it found no evidence that US foreign policy was influenced by it.
Hunter Biden's presence on the Burisma board led to an impeachment trial against Donald Trump earlier this year.
Mr Trump was accused of pressing Ukraine to probe what the Bidens were doing in the country, and using military aid as a bargaining chip.
He was impeached by the Democratic House but cleared by the Republican Senate.
The 87-page report called the younger Biden's role at a company suspected of corruption "awkward" and "problematic" at a time when the US was trying to help clean up corruption in Ukraine.
However, the report found little additional information that had not already been publicly revealed in news reports and testimony to the impeachment committee.
Mr Trump has claimed that Mr Biden meddled in Ukraine to help his son's business interests, but lawmakers found no evidence of this.
What is the background?
The impeachment trial centred on a phone call Mr Trump made to the Ukrainian president in which he seemed to pressure him to open an inquiry into the Bidens.
Mr Trump claimed that Mr Biden, who was vice-president under President Barack Obama from 2009 to 2017, had sought to remove a Ukrainian prosecutor in order to assist energy firm Burisma, where Hunter Biden worked.
But the prosecutor whom Mr Biden was seeking to remove due to allegations of corruption, Viktor Shokin, had also been criticised by European and US officials - including Republicans.
How damaging is this report to Joe Biden?
If there is an autumn bombshell coming at the Biden campaign regarding the former vice-president's family involvement in Ukraine or China, this report from Senate Republicans isn't it.
Calling Hunter Biden's position on the board of a Ukrainian gas company "awkward" and "problematic" is weak sauce compared to the conservative media frenzy and Donald Trump's own accusations lobbed at Joe Biden's son earlier this year.
Beneath the headlines, however, the report does detail the breadth of Hunter Biden's connections to questionable foreign interests and business leaders in Ukraine and China - creating "criminal financial, counterintelligence and extortion concerns". It suggests Joe Biden's son was profiting from his family name - a potential conflict of interest that is unsavoury but not unusual in Washington's corridors of power.
The report acknowledges there are still unknown details, but time is running out for Republicans to turn this topic into something voters will care about. If Joe Biden wins in November, however, his political opponents are likely to continue to dig, in hopes of building on the information in the report to come up with more tangible evidence of misconduct that could damage his presidency.
What did the report find?
The Senate Homeland Security Committee's report found that two members of the Obama administration had complained in 2015 to the White House about Hunter Biden's new lucrative role on the board of Burisma.
"Hunter Biden's position on Burisma's board cast a shadow over the work of those advancing anticorruption reforms in Ukraine," the report says.
But the report failed to find evidence that Obama administration policy was influenced by the younger Biden's job, instead citing concerns from officials who called his job "awkward for all US officials pushing an anti-corruption agenda in Ukraine".
"Hunter Biden's position on Burisma's board was problematic and did interfere in the efficient execution of policy with respect to Ukraine," the report says, adding that Biden relatives "cashed in on Joe Biden's vice presidency".
But it continues: "The extent to which Hunter Biden's role on Burisma's board affected US policy toward Ukraine is not clear."
Ahead of the report's release - just six weeks before the presidential election - committee chairman Ron Johnson said in interviews that it was the committee's goal to release it before the election in order for voters to learn more about Mr Biden and his family before casting their ballot.
What has reaction been?
The Biden campaign rejected the report as an attempt by Republicans to undermine him and distract from the coronavirus crisis.
Last week Utah Republican Senator Mitt Romney, slammed the committee's investigation as "a political exercise".
"It is not the legitimate role of government, for Congress or for taxpayer expense, to be used in an effort to damage political opponents," he said.