Trowbridge is a district, community and coterminous electoral ward on the eastern edge of the city of Cardiff, capital of Wales.

The community and electoral ward includes some or all of the areas of the St Mellons estate and Trowbridge, as well as part of the Wentlooge Levels between the mainline railway and the coast.

[2] It is bounded by the village of Old St Mellons to the north; Marshfield (in Newport principal area) to the east; and Splott and Rumney to the west.

Trowbridge largely dates from the second half of the 20th century, when housing spread east from Rumney onto the farmland of the area.

In 2019, plans for a new £150m waste incinerator plant was proposed by Mor Hafren Bio Power, off Newlands Road in Wentloog, Trowbridge.