Members of pro-Palestinian group Boycott, Divestment and Sanctions (BDS) have been involved in a year-long dispute with Woolworths.
They have demanded that Woolworths refrain from stocking Israeli products and have promised to demonstrate against the singer's partnership with the retail group.
On Friday, BDS won a morale-boosting victory when the Western Cape High Court reversed the City of Cape Town's restriction on the number of protesters allowed at the Pharrell Williams concert.
The court found the restriction to be unconstitutional, and gave the go-ahead for 16,000 people to protest until 4pm.
The City of Cape Town was ordered to pay all legal costs.
In a press statement, BDS said they expected Pharrell Williams to face “the largest protest any artist would have faced since the end of Apartheid”.