It carries the Great Western Main Line from Paddington, London to Wales and the West across the River Thames.

During the 1890s, a second bridge was built immediately parallel to the original structure, enabling the railway to be expanded to a quadruple track configuration.

The structure has often been regarded as being of an exceptional size for the era; to better accommodate such dimensions, Brunel incorporated a series of internal longitudinal walls and voids to lighten the superstructure, which also reduced the cost and time needed to construct it.

[3] It also has several differences, such as the lack of stone quoins, while the plain uncut bricks form a jagged pattern where they meet the faces of the bridge.

[3] During the 1970s, the Great Western Main Line was subject to extensive reengineering work to enable 125 MPH running for the newly introduced Intercity 125 services; accordingly, some changes were made to Moulsford Railway Bridge.

[8] During the 2010s, the railway lines crossing the bridge were electrified, requiring the installation of 25 kV 50 Hz AC OHLE across the structure.