Clad in rusticated weatherboards with a corrugated-iron roof, Seddon is a slender gable station. Its architectural origins are a little obscure. Much of the detailing is similar to that of a class 4 lean-to station and it may also be a gabled version of a class 5 station. On the platform elevation the central arched lobby is flanked by two single-pane sash windows, reminiscent of the class 4 1obby arrangement. To the left is another sash window. The former postal lobby, to the south of the main entrance, is beside the ladies' toilet. Access to the latter is gained by a side entrance.
Seddon was erected as part of the Blenheim-Awatere railway and was completed in 1902. The railway followed the next year. The contractors were T. May and J. McKinlay. Provision was made for postal and telegraph work to occupy one end of the building. Seddon was the southern terminal of the Main North Line for nine years until extended to Ward in 1911, and it was nearly 30 years before work on linking the two railheads began again. Seddon had a very quiet history serving the local farming community. In 1966 an earthquake brought down the chimney and in 1969 public toilets were mooted but the idea was abandoned. From 1986 the station was retained for track gang use hut has recently been sold. The platform is still used by Coastal Pacific passengers.