We describe a new low-frequency wideband radio survey of the southern sky. Observations covering 72–231 MHz and Declinations south of
$+30^\circ$
have been performed with the Murchison Widefield Array “extended” Phase II configuration over 2018–2020 and will be processed to form data products including continuum and polarisation images and mosaics, multi-frequency catalogues, transient search data, and ionospheric measurements. From a pilot field described in this work, we publish an initial data release covering 1,447
$\mathrm{deg}^2$
over
$4\,\mathrm{h}\leq \mathrm{RA}\leq 13\,\mathrm{h}$
,
$-32.7^\circ \leq \mathrm{Dec} \leq -20.7^\circ$
. We process twenty frequency bands sampling 72–231 MHz, with a resolution of 2′–45′′, and produce a wideband source-finding image across 170–231 MHz with a root mean square noise of
$1.27\pm0.15\,\mathrm{mJy\,beam}^{-1}$
. Source-finding yields 78,967 components, of which 71,320 are fitted spectrally. The catalogue has a completeness of 98% at
${{\sim}}50\,\mathrm{mJy}$
, and a reliability of 98.2% at
$5\sigma$
rising to 99.7% at
$7\sigma$
. A catalogue is available from Vizier; images are made available via the PASA datastore, AAO Data Central, and SkyView. This is the first in a series of data releases from the GLEAM-X survey.