The invention provides a biodegradable packaging material, a method of manufacturing the same, as well as products made of the material. There is coextruded onto a fibrous substrate (1) a multilayer coating comprising innermost and outermost layers (2, 4) of a blend comprising 20-95 wt-% of a higher melt index polylactide and 5-80 wt-% of another biodegradable polymer such as polybutylene succinate, and a middle layer (3) containing a lower melt index polylactide alone. The goal is to increase machine speed in coextrusion while maintaining good adhesiveness to the substrate and good heat-sealability of the coating. The products include disposable drinking cups and board trays, as well as sealed carton packages for solids and liquids.