The strike will force about 130 of the US-based retailer's supermarkets to close, while more than 100 other stores will operate with reduced hours, SIL union President Juan Moreno, whose members voted to strike, said.
Walmart Chile stores will be open only half a day, operating either in the morning or in the afternoon, the Efe news reported.
Walmart operates 371 stores under the the Hiper Lider, Lider Express, Central Mayorista, Superbodega Acuenta and Ekono brands in Chile
Union members rejected management's latest offer two weeks ago, but the start of the strike was postponed when Walmart requested Labor Board mediation on July 3.
The union said the talks held since then went nowhere, forcing workers to walk off the job on Wednesday.
Walmart Chile workers are seeking a 4 per cent wage hike since they are being asked to perform multiple functions as the retailer automates more of its services.
Management, for its part, offered a 3 per cent pay increase plus a bonus of 50,000 pesos (about $72).
The two sides did agree on a transportation bonus equivalent to two daily trips on public transit.
Moreno told Radio Cooperativa that the union had not rejected management's proposal "in and of itself," but "what happened is that we did not reach an agreement within the framework of mediation because we had been having conversations."
"The time limit expired and the company did not make a proposal that would have taken into account the change to multiple functions for workers," Moreno said, adding that the planned changes "are abysmal" and the company's offer "insufficient for such a significant" shift in store operations.
The union leader said he hoped that Walmart Chile "could retrain" workers, noting that the union was open to discussing this issue.
Walmart Chile, for its part, said it was regrettable that workers had decided to strike, adding that management made a full effort to "reach an agreement."
The retailer said the strike would mostly affect the Super Bodega Acuenta and some Hiper Lider and Lider Express stores, and an operations plan was implemented "to ensure adequate service to customers."
( With inputs from IANS )