Tickets for the music event go on sale on April 1, but are only available to those who have registered interest.
The outdoor retailer - which has 285 stores across the UK - will have two stands at the festival this year, selling a range of products including wellington boots, fuel, stoves and waterproof jackets.
Blacks Leisure issued a profit warning at the start of the year, following an earlier warning about disappointing sales because the Glastonbury festival was cancelled last year and because of an exceptionally mild autumn.
Like-for-like sales were down 6 per cent for the five weeks ending December 30 and total sales - including new stores - slid 3.5 per cent for the same period.
For every form distributed in store, Millets will donate 10p to WaterAid, Glastonbury Festival's chosen charity.
A Millets spokesperson said: 'We are very pleased to be working in partnership with Glastonbury as their high street retail partner for 2007. We are really excited about this year's festival season, because we have an extended camping range that includes Eurohike Flash tents that pitch in seconds and the Eurohike Mix and Match tents with an assortment of funky, fun patterns for those who like to stand out from the crowd.'