Negombo Lagoon is a large estuarine lagoon in Negombo, south-west Sri Lanka.

It is linked to the sea by a narrow channel to the north, near Negombo city.

It is surrounded by a densely populated region containing rice paddies, coconut plantations and grassland.

The lagoon has extensive mangrove swamps and attracts a wide variety of water birds including cormorants, herons, egrets, gulls, terns and other waders.

Negombo, Katunayake, Seeduwa are some nearby towns.