Police officers have been deployed across South Africa because of fears that anti-immigration protests could turn violent as President Cyril Ramaphosa urged those planning to take part to do so without "intimidation, threats or ultimatums".
The planned protests mark an unofficial deadline set by campaigners for all undocumented foreigner to leave the country.
Many have already fled to escape violence and intimidation. South African police say 25,000 have been repatriated so far. Most are from other African countries.
One undocumented Malawian told the BBC he was "happy to be going back" but "heartbroken" to be leaving behind four young children.
Johannesburg, where one of the protests is planned, is unusually quiet.
All the shops in the vicinity of where marchers are due to gather are closed, while police visibility is high on the city's major streets.
Police said that five people were arrested in Johannesburg's biggest township, Soweto, for allegedly looting a foreign-owned shop.
Five people were also arrested for allegedly breaking into a tuck shop in Hammarsdale in KwaZulu-Natal province.
Many businesses in central Durban, the main city in the province, are shut.
Ramaphosa has repeatedly warned demonstrators to act peacefully and responsibly, while also accepting the need for immigration reforms.
"Some foreign nationals who live in South Africa are here lawfully," he reminded citizens in his weekly newsletter, external.
"They work, study, raise families, invest in our economy and contribute positively to our society. They too are entitled to the protection of our laws and our Constitution.
"The right to protest and freedom of expression does not allow people to threaten or intimidate others, or to engage in acts of vandalism or violence," he wrote.
There are more than three million documented foreign nationals in South Africa, according to official figures.
Ahead of the deadline, thousands of migrants have been awaiting processing in temporary camps for several weeks out of fear for their safety.
In Durban, which has seen some of the biggest protests, white tents housing mostly Malawians are being dismantled as authorities race to clear the transit camp.
Women in colourful sarongs sat on top of their belongings, waiting in line to board a bus home to Malawi.
One man, Nelson Mbewe, said he had gone to South Africa in search of employment to support his family in Malawi.
"But we've faced challenges - they're saying we should go back home because we do not have the right documents," he told the BBC.
"They say we are Makwerekwere" - a xenophobic slur used to refer to African migrants from other countries - Mbewe said.
"It's their country, so what can we do? That's why we have accepted that we just have to [unwillingly] go back home."
Hassan Phiri, a Malawian who is still waiting to be processed, had a message for the protesters.
"All I want to say to South Africans is that we are all one. No matter what is happening, no matter what will happen, Africa must remain Africa.
"Africa can't be Africa without South Africa... without Malawi, without anywhere," he told the BBC, adding: "So whatever will happen, we must love each other and stick together as Africa."
