Mr Stevens was already facing a tough re-election battle in November
Alaska Senator Ted Stevens has been charged with making false statements on his Senate financial disclosure form.
The Republican lawmaker has been under investigation for his involvement with Veco, an oil company whose executives have confessed to bribing officials.
In Mr Stevens's indictment, officials alleged that he failed to disclose $250,000 worth of work done on his house free of charge by Veco employees.
Mr Stevens, 84, is the longest-serving Republican in the US Senate.
He has not immediately responded to the indictment.
Veco CEO Bill Allen, who pleaded guilty to bribery charges in May 2007, has testified that he arranged for employees of his company to assist Mr Stevens with renovations to his house in Girdwood, Alaska.
Officials said Mr Stevens also received new vehicles in exchange for older ones worth far less from the energy company, as well as other household goods.
Around the time that the house renovations were taking place, Veco won a $170m (£85m) federal contract to provide the National Science Foundation (NSF) with polar and Arctic research support, despite having no previous experience in the field, the Anchorage Daily News has reported.
Mr Stevens, as a senior member of the Senate Commerce Committee, would have had oversight of the NSF.
"Stevens knew the requirements of the financial disclosure forms and knowingly and intentionally sought to conceal and cover up his receipt of things of value by filing financial disclosure forms that contained false statements and omissions concerning Stevens' receipt of these things of value," the indictment said.
Law enforcement officials have also been looking into whether Mr Stevens improperly pushed for changes to fishing rules that would have benefited his son, an Alaska lobbyist.
Mr Stevens's Senate seat is up for grabs this November, and polls suggested that he was facing a tough re-election battle, even before the indictments were brought against him.