This junction was formed in 1847 when the original route of the Kilmarnock and Troon Railway (upgraded and converted to standard gauge) was linked by a new connection to Kilmarnock Junction, allowing Kilmarnock [1st] to replace Kilmarnock (St Marnocks) as the terminus of the line from Troon.
This new connection left Kilmarnock (St Marnocks) at the end of s short branch. A new St Marnock Mineral Depot was built at the junction at the start of the branch.
A signal box opened at the junction in 1893. The branch was cut back to the mineral depot, now approached from the east via a reversing spur.
The box and yard closed in 1974 on singling of the line.
The railway remains open.