Many diners were eating hamburgers inside the recently opened Wendy's outlet in South Dunedin but many passing motorists were also tooting their horns to show support for the protesters, led by the Unite Union, during the event.
Protest organisers said it began about 10.30am and continued until shortly after 2pm.
More than 30 protesters were involved shortly after 11am.
Ben Peterson, a Christchurch-based organiser for Unite, said the protest had aimed to ''raise awareness about zero-hour contracts and put pressure on'' to encourage the fast-food industry to provide more protection for workers over their hours of work.
Such contracts often require staff to remain ready to work for one employer only, but they are not contractually guaranteed set hours of work.
Wendy's chief executive, Danielle Lendich, last week said that Wendy's did not use zero-hour contracts, and did not roster workers for fewer than 10 hours a week without their consent.
And, she said, Unite was targeting Wendy's for ''political gain''.
Mr Peterson said zero-hour contracts were common in several big takeaway food chains, and they created great insecurity for staff.
Even when staff had been able to work a good number of hours each week, there was always the risk that the hours, and employee income, could suddenly drop in the future, including at Wendy's.
And that uncertainty made it hard for staff to plan how to pay family bills, and to gain bank loans to buy a house, because their projected working hours, and therefore their income, remained unpredictable, he said.
No further comment was immediately available from Wendy's management on Saturday.
