Mohamad Hammoud, 28, accused of being the leader of the cell, was convicted of 16 counts that included providing material support to Hezbollah.
Chawki Hammoud, 37, was found guilty of charges including cigarette smuggling, credit card fraud, money laundering and racketeering.
Jurors deliberated 21 hours over three days. On Friday afternoon, they told the judge they were deadlocked on one count, a charge that Mohammad Hammoud conspired with others to provide material support for Hezbollah.
Mullen sent them back to deliberate more, and they returned a verdict two hours later.
If sentenced to the maximum allowed by federal guidelines, Mohamad Hammoud could get 155 years in prison. That sentence could be increased if U.S. District Court Judge Graham Mullen rules that Hammoud lied when he took the stand in his own defense.
Chawki Hammoud faces a maximum of 70 years.
The brothers are accused of running a cigarette-smuggling ring that sent cheap North Carolina cigarettes to Michigan, where they were resold without paying that state's higher taxes.
The government says some of the profits were directed to Hezbollah, which opposed an 18-year Israeli occupation of southern Lebanon that ended in May 2000.
Under a 1996 anti-terrorism law, it is illegal to provide material support to Hezbollah and other organizations labeled terrorist by the State Department.
Only Mohamad Hammoud was charged with providing material support to Hezbollah, although both brothers faced a racketeering count that accused them of membership in the support cell.
Natives of Lebanon, the brothers have resident status here but are not U.S. citizens. They could be deported after they serve their prison sentences.
Mohamad Hammoud's lawyer, Deke Falls, denied his client was a member of Hezbollah. He said his client's sympathy for the group was natural for someone who grew up in a country torn by civil war and the strife resulting from the Israeli occupation.
The trial resulted from a prosecution that began with the July 2000 arrest of 18 people, most of them from Lebanon, on cigarette-smuggling charges.
Nine months later, eight men — all Lebanese nationals — and one woman from the earlier group were accused of involvement in a Charlotte-based cell of Hezbollah.
Seven defendants ultimately pleaded guilty, including Mohamad Hammoud's American wife, Angie Tsioumas, and Said Harb, originally the only defendant charged with providing material support to Hezbollah.
After Harb pleaded guilty, prosecutors filed a superseding indictment in March that charged Mohamad Hammoud with material support and indicted several other men who are not in custody. That group includes Sheik Abbas Harake, to whom Harb said Mohamad Hammoud asked him to take $3,500 during a 1999 trip to Lebanon.