The 32-year-old was driving an articulated lorry when it was stopped by police on Monday as part of routine cargo checks as it arrived in the port of Bari on the Adriatic sea.
The lorry was searched as it disembarked from a British ship in the port after travelling from Greece.
Officers uncovered 41kg of "high purity" heroin inside cardboard boxes of breadsticks, produced by a Greek company and bound for Lancashire.
The Scots driver was taken into custody alongside another 42-year-old man, believed to be Irish, following the raid.
In a statement, the Guardia di Finanza said the drugs had value of more than €20m (£16m).
A spokesman for the Foreign Office said: "We can confirm the arrest of two British nationals on November 26 in Bari, Italy."