You Do Need power plug adapter while traveling from Malawi to French Guiana.

Here is Why You Need An Adapter

The outlet and plug type used in French Guiana are C, D and E and in Malawi is G. This is how they look like.

Malawi

In Malawi, outlets of type G are in use.

Type G

French Guiana

In French Guiana, outlets of type C, D and E are in use.

Type C

Type D

Type E