Money will be directed towards installing machines to carry out processes such as product testing and the straightening of beams which are currently done by hand.
But the move will lead to a net reduction of 98 jobs at the Teesside plant and Corus said consultations have already begun with staff and trade unions.
Details of the job cuts emerged just days after Corus rewarded its chief executive with a 19 per cent rise in his pay package to £1.43 million last year.
Corus - formed from the merger of British Steel and Dutch firm Hoogoevens in 1999 - returned to the black last year after benefiting from rising steel prices and the benefits of a major restructuring.
Its modernisation programme - known as Restoring Success - recently involved plans to invest £130 million at one of its biggest steel-making plants at Scunthorpe, where it will make structural sections, rail and wire rods.
The Anglo-Dutch group has 48,300 employees in more than 40 countries and generates sales of £9.3 billion a year.
Its beam mill on Teeside is part of Corus's Construction and Industrial business, which employs 517 workers at the plant itself and a further 700 staff locally in engineering and support functions.
Corus also operates a cast products business on Teesside which exports slabs and employs 1,700 staff.
Andrew Page, managing director of CC&I, said: 'Today's announcement to invest in the Teesside beam mill is extremely good news for the mill and for our sections business.''