The shipment of Grad rockets and ammunition for automatic rifles and machine guns was seized late Tuesday at a random army checkpoint near the town of Baalbek, a stronghold for the Shiite Muslim militant group.
Six Hizbullah members in the truck were let go but the confiscated weapons were taken to army barracks nearby.
It was not clear whether the militants' were transferring the weapons within the country or bringing the shipment in from neighboring Syria, as they have reportedly done in the past. Also, the shipment's destination was not known.
There was no immediate comment from Hizbullah on the weapons' seizure.
Under a UN Security Council resolution that halted last summer's fighting between Israel and Hizbullah, any transfer of weapons to groups other than the government is illegal.
But the guerrilla leaders have boasted that they have replenished their stocks of rockets after the fighting.
Hizbullah has urged the government to abide by its own policy, proclaimed in 2005, to support the "resistance" in the south - which is Lebanese shorthand for the guerrilla group.
But the guerrillas has since November left the government along with its allies and joined the opposition seeking to topple the US-backed prime minister, Fuad Saniora.
In February, authorities seized a truck bringing military supplies for Hizbullah in a Beirut suburb. The group acknowledged the shipment was theirs and demanded it be returned but the government refused.