Today, passenger services on the 64.5 km-long Hamburg Eidelstedt–Neumünster section are operated by AKN.

On 8 September 1884, the Altona-Kaltenkirchner Eisenbahn-Gesellschaft (Altona-Kaltenkirchen Railway Company), which was established in the previous year, opened the line from Altona to Kaltenkirchen for passenger traffic.

Accordingly, a central buffer coupling was selected, which was also necessary at the beginning because of the sharp curves of the line.

It ran over the Hamburg-Altona link line using folding track (this was able to fold to give one line or the other a clear passage), running on street level from Schulterblatt station (about where Haubachstraße now runs) to the Viktoria barracks.

In 1893, the link line was rebuilt on an embankment to the north of the Holsten Brewery and Holstensraße station was built, as it exists today, with the AKE operating at street level on the Gählersplatz–Nebenzollamt section.

In 1902, a connection was built to the state railway in Eidelstedt, where freight wagons were transferred.

On 17 December 1912, the line between Altona and Eidelstedt was laid parallel to the Hamburg-Altona–Kiel railway on the current route because of the increasing traffic of the Altona-Kiel road.

After 1957, the track was operated with a simplified form of train control using instruction over the radio.

The platforms between Eidelstedt and Kaltenkirchen were raised to a uniform height of 76 cm and extedended to a length of 100 metres.

The operation of traffic on the new line started on 28 August 2000 and about a year later the work was completed and the new buildings were officially opened.

Since 2006, the line between Schnelsen and Quickborn has been upgraded; double track has been in operation between Bönningstedt and Hasloh since 28 October 2007.

The Hasloh–Quickborn Süd section has been duplicated since May 2011; this was followed by the commissioning of double track between Halstenbeker Straße and Schnelsen station in October 2011.

In the medium term it is planned to complete the duplication and to integrate it into the Hamburg S-Bahn network.

The entire line is controlled from the AKN operations centre in Kaltenkirchen via local electronic interlockings.

All stations on the southern sector from Kaltenkirchen to Eidelstedt are equipped with electronic passenger information displays with the exception of Schnelsen; on the northern section individual stations such as Bad Bramstedt and Neumünster Süd are so equipped.

Elsensee station lay between Hasloh and Quickborn Süd and was mainly used by employees of the Thörlschen margarine factory.

This was closed during World War II due to air raids and moved to Hamburg-Harburg.

AKN's local trains now run mainly at 20-minute intervals on the Eidelstedt-Kaltenkirchen section.

The busiest part of the line is the section between Ulzburg Süd and Henstedt-Ulzburg, which regularly has up to nine trains per hour in each direction.

With the extension of the Hamburg S-Bahn, the southern terminus for passenger services was moved from Kaltenkirchener station in Altona to Langenfelde in 1962 and finally to Eidelstedt in 1965.

Initially, there was no direct transfer traffic with the state railway, all freight had to be transhipped.

Since the beginning of operations until the end of the Second World War, the AKN had a total of 28 steam locomotives, which handled all traffic until the arrival of the first railcars, built in 1930.