The Neumünster–Ascheberg–Eutin–Neustadt line was opened on 31 May 1866. The line was operated by the Altona-Kiel Railway Company (, AKE), which was nationalised in 1884. In railway timetables, the line was soon shown in three sections. From Ascheberg (Holst) to Eutin it was considered part of the Kiel–Lübeck railway. The easternmost section from Eutin to Neustadt was now managed as a separate line (the Eutin–Neustadt railway).
