Flash floods caused by days of torrential rain have swept away roads and bridges, destroyed thousands of hectares of crops and raised fears of a cholera outbreak in the southern half of the country.
The weather service is warning of more heavy rain in the next two to three weeks.
"So far, the death toll stands at 176 people and we fear the number will rise because several are missing and some parts are inaccessible," Chilima said.
The United Nations' World Food Programme (WFP), one of several relief agencies rolling out assistance, said 110,000 people had been displaced, an increase from a government estimate of 70,000 earlier this week.
"Many more are likely to require assistance. With more rain forecast, there is concern that these numbers may rise," the WFP said.
The agency is airlifting more than 100 tons of high-energy biscuits to meet the immediate needs of those affected.
"Ready-to-eat food will be prioritised for the most vulnerable people, particularly children, who have been displaced from their homes and have no access to food or cooking facilities," it said.
The crop damage has raised fears of a poor harvest. Last year, Malawi's farmers harvested 3.9 million tonnes of the staple crop, maize, providing a surplus of almost one million tonnes.
The wet weather has also wreaked damage in neighbouring Mozambique, which has been hit by catastrophic floods in the past.
Bridges have collapsed and the newly elected government has declared a "red alert" in central and northern areas. South Africa has sent military helicopters, divers and medics to assist with rescue and relief efforts.