Bridget Kelly, then-deputy chief of staff to Christie, and Bill Baroni, whom the governor appointed deputy executive director of the Port Authority of New York and New Jersey, were found guilty on all counts, prosecutors said.
The 12-person jury took five days to reach the verdict. The convictions include wire fraud, depriving people of their civil rights and conspiracy.
A third Christie aide, David Wildstein, had pleaded guilty.
Thousands were affected in the town of Fort Lee in September 2013, with children prevented from going to school and emergency response times delayed when traffic was forced into a solitary lane on the George Washington Bridge.
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The verdict will embarrass the Trump campaign, four days before the election at a time the Republican presidential candidate has been gaining momentum in the polls.
The trial spotlighted a bruising political climate around some of those closest to Christie, who is chairman of Trump's transition team preparing for the New York billionaire's possible victory.
"Time for some traffic problems in Fort Lee," Kelly wrote in one email to Wildstein. To cover up the crime, they claimed the lane closures were part of a traffic study, which the prosecution called a sham.
"Is it wrong that I am smiling?" Kelly wrote in a text message to Wildstein when told about Fort Lee Mayor Mark Sokolich's complaints.
Their "cruel and callous" scheme "disrupted and endangered the lives of thousands," assistant US attorney Lee Cortes told the federal court in his summation last Friday in Newark, New Jersey.
The trio wasted government money, resources and employees "just to mess with people so they could send a clear and nasty message," the prosecutor said.