Malawi’s main airport for international flights is at Lilongwe. Although there is an airport in Blantyre with less frequesnt flights.
You can fly into Lilongwe and travel to Blantyre by bus or plane but this may necessitate a night in Lilongwe. If you fly into Blantyre we should be able to pick you up from the airport. South African Airlines fly to Blantyre for Johannesburg every Wednesday and Saturday. Make sure you sort out your visa requirements with the Malawian Embassy before you leave.
South African Airways (www.flysaa.com) flies twice per week to/from Jo’burg (with connections to Durban, Cape Town etc); Kenya Airways (www.kenya-airways.com) flies four times per week to/from Nairobi.