The cash will be spent on new packaging lines, an increase in multi-packing capability and enhancements to staff facilities, and would create several new jobs, said Kettle Foods Europe md Jeremy Bradley.
"We are continuing to drive strong growth in a tough marketplace and see a lot of opportunity to sustain this trend. It's a credit to the work of the Norwich team that Diamond is making this investment, which supports our plans for growth and will create a number of new jobs for the region."
Significant growth for Kettle brand
The Kettle brand was experiencing significant growth driven by strong sales of its new ridged range, sharing bags and increased penetration in impulse channels and export markets, said Bradley.
The brand also performed particularly well in the festive season, with sales up 13% in the 12 weeks to December 25 and up 19% in the four weeks running-up to Christmas, he said.
California-based Diamond Foods acquired Kettle Foods UK from Lion Capital in February 2010 in a £402m deal.
A leading processor of nuts, popcorn and other snacks with distribution in more than 80% of US supermarkets, Diamond also has a large export business.