As it has always been part of the Main South Line (originally the Canterbury Great Southern Railway), this name has never been officially used to refer to the track itself.

Part of the Lyttelton Line was originally operated as New Zealand's first public railway, connecting the city of Christchurch to a wharf at Ferrymead.

Because of the inaccessibility of the harbour at Lyttelton, shipping traffic berthed at the Ferrymead wharf from which people and supplies were transported to Christchurch by train.

It was found that the separation of passenger and goods traffic led to a reduction in operational costs, with savings made in fuel and wear-and-tear on machinery.

Primarily motivated by a desire to eliminate the smoke nuisance in the tunnel and to cater for an increasing amount of traffic, the line was electrified in 1929.

The frequency of train running in the early years of operation was limited more by the inadequacy of port facilities rather than the capacity of the railway.

All trains of this period on the Lyttelton Line were mixed, with the amount of traffic being insufficient to justify separate freight and passenger services.

This remained the case until 5 November 1872 when a new timetable scheduled four goods services per day to accommodate the increasing amount of traffic.

This method of operation remained unchanged until the opening of goods sheds on Cashin Quay in 1965, which heralded the era of containerisation.

From the wharf, the express services ran non-stop to Christchurch, where passengers could avail themselves of refreshments or the station dining room before the train continued on to Dunedin.

However, it was already beginning to feel the effects of competition from air services, which were greatly improved with the National Airways Corporation (now Air New Zealand) introducing Boeing 737-200 aircraft to its main routes in 1968, and by the Railway Departments own road-rail ferry service between Picton and Wellington, which commenced in 1962 and provided considerable time savings, especially to those north of Christchurch.

Other options tried or investigated for this line were duplication, and an attempt in 1909 to convert a Wf class steam locomotive to oil burning for operation through the tunnel, a move that proved to be only partially successful, and a study done into the idea of using diesel motive power through the tunnel, an option that was abandoned due to the immaturity of the technology at the time.

The government commissioned British consultants Merz & McLellan in 1925 to report on various proposals for electrification of parts of the rail network.

It concluded that if the North Island Main Trunk through Johnsonville were electrified, that would delay the need for the Tawa Flat deviation.

Christchurch thus became the first city in New Zealand to receive an electric train service, preceding those inaugurated in Wellington in 1938 (to Johnsonville), 1940 (to Paekakariki) and 1953 (to Taita).

With the sub-station being located in Woolston, roughly halfway between both termini of the electrified section, the greatest distance travelled by the current was a little more than 3 miles (4.8 km).

As the entire line was double-tracked, with the exception of the tunnel, there were two parallel paths to supply current to, including some electrified sidings.

Work on building a new maintenance facility began at Waltham in 2020,[2] with the Scenic Journeys Servicing Centre, which provides for carriage washing, refuelling, waste handling, watering and has an inspection pit.