The placard-carrying protesters picketed outside Groot Schuur Hospital in Cape Town, South Africa, and demanded that Chiwenga be sent back to Zimbabwe where his government has allegedly destroyed the health sector.
Chiwenga is receiving treatment in South Africa, the second time in four months, after falling ill last week.
According to media reports, Chiwenga had initially checked in at a private hospital last week but had to travel to Cape Town for further treatment.
He is widely seen as the power behind President Emmerson Mnangagwa and the front-runner to succeed him. He led the coup that ousted former president Robert Mugabe in November 2017.
The former army general is believed to still wield influence in the military, which has been accused of unleashing a reign of terror since last month’s anti-government protests.
Chiwenga has also been criticised for his handling of a strike by junior doctors in December 2018, which saw most public hospitals literally shutting down as the government responded by dismissing all the strikers.