The improved forecast is mainly down to strong Easter sales and an expanded store network at home and abroad.
In a stock market filing, Jumbo said it was targeting earnings growth of about 21.4 percent in 2008 after an 18.3 percent sales rise in the 10 months to April.
Earlier in the year, it had said it was targeting earnings and sales growth of up to 15 per cent.
The firm, which also sells stationery and baby clothes, said sales were expected to grow by 17.4 percent in the same period.
Net income and revenues are seen rising to 82.4 million and 402.3 million euros, respectively, according to Reuters calculations.
In December, Jumbo launched two new stores in Athens and Sofia in Bulgaria, bringing its total number of outlets to 41.
It plans to open three more stores in Greece by June 2009 and further penetrate the Bulgarian market by opening up to 12 stores.