Republican and Democratic leaders on the panel vowed to follow the intelligence "wherever it leads".
The investigation will look into Russia's cyber activity and intelligence practices.
Interviewees will include members of the current US administration and President-elect Donald Trump's team.
A statement, released by the committee late on Friday, said, "We believe that it is critical to have a full understanding of the scope of Russian intelligence activities impacting the United States."
The committee will examine whether there were any contacts between Russia and people associated with the US political campaigns.
It said subpoenas would be issued "if necessary to compel testimony".
The bulk of the work will be done behind closed doors, although the senators say they will hold open hearings when possible.
"The committee will follow the intelligence wherever it leads.  We will conduct this inquiry expeditiously, and we will get it right," said the statement.
The senators said they would produce both classified and unclassified reports on their findings.
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President-elect Trump announced, on Twitter on Friday, that his team will also produce a "report on hacking" within 90 days.
It follows the released of an unproven dossier alleging that Russian security officials have compromising material on Mr Trump, which could make him vulnerable to blackmail.
The US president-elect said the claims were "fake news" and "phoney stuff".
The US released an unclassified intelligence report earlier this month, claiming that Russian President Vladimir Putin had ordered the hacking of Democratic Party emails to damage Mr Trump's Democrat rival, Hillary Clinton, and influence the election.
It also said Russia used state-funded propaganda and paid social media users, or "trolls", to launch online attacks.
In December, US President Barack Obama expelled 35 Russian diplomats from the country in response to the hacking allegations.
Russia says allegations that it ran a hacking campaign to influence the US presidential elections are "reminiscent of a witch-hunt".
The US Senate's Intelligence Committee will investigate claims that Russia attempted to meddle in last year's presidential elections.