Profits rose to £7.5m in the 28 weeks to 7 August, the society said, with sales up 0.9% to £193.1m.
CEO Richard Samson said the results were "credible". He added: "All the signs are that there will be no easing of the tough economic climate through the remainder of this year and probably throughout 2011.
"However, our strong financial position has enabled us to invest with no net borrowings and we are well placed."
The society is also continuing its store development programme. It recently acquired a food store in Ipswich and is building a new store in Colchester. It also carried out major store refurbishments in two food stores during the period.
East of England Co-op is the UK's third-largest co-op, with more than 200 stores across Norfolk, Suffolk and Essex.