NS Reizigers and subsidiary Abellio Regio are to operate services between Alphen aan den Rijn and Gouda from December 2016.
NS and Abellio beat Arriva to the 15-year concession, which is worth more than €3 million a year.
Under the terms of the contract, the new operator is investing in six new trains to increase the number of passenger journeys on the South Holland line by 55 per cent.
A six-week statutory cooling down period is now underway before the award can be finalised.