Service was resumed at 1700 CET (1500 GMT).
Torching tires and blocking traffic, the French workers protested expected job cuts in the French port city of Calais linked to Eurotunnel's sale of its ferry service. Both freight and Eurostar passenger trains suspended their services.
The Eurostar train service carries about 10 million people a year across the English Channel, with summer marking the height of the tourist season.
An Associated Press photographer saw the striking workers swarm the tracks on Tuesday afternoon. It was the second time in a week port workers paralyzed the train lines.
On June 23, they blocked the highway exit leading to the tunnel, prompting migrants who are camped in Calais by the thousands to try and stowaway on the slow-moving freighters in hopes of reaching England. Then, later that day, they blocked the tracks themselves.
Traffic resumed the following day.