Robert Dyas will open shop-in-shops in three Somerfield stores in an initial six-month trial before committing to a full-scale roll-out next year.
The deal was brokered by former Kingfisher colleagues Rob Cissell - Robert Dyas chief executive - and Somerfield retail director John Cleland.
Cissell said: 'I am very confident it will be a success. The two estates complement each other. It's a good opportunity for us to expand outside of our footprint. Somerfield has highlighted 100 stores that we could go into.'
The deal could allow Robert Dyas to more than double its existing portfolio of 95 stores.
The first 2,000 sq ft (185 sq m) shop-in-shop will open in Somerfield's outlet at Rayleigh, Essex, on Monday. It will sell 2,000 SKUs of DIY, hardware, home and garden products.
A further two concessions will follow at Braintree and Chelmsford this autumn.
The concessions will be staffed by Robert Dyas employees and the chain will pay a percentage of turnover to Somerfield.
Somerfield director of new business Jon Dunman said: 'Working with Robert Dyas, we can benefit from their experience and give our customers something extra.'
Planet Retail analyst Bryan Roberts said: 'Success depends on execution. If Somerfield and Robert Dyas can get that spot-on then there is no reason why it won't be successful.'
The venture is part of the grocer's efforts to extend its non-food offer and take advantage of surplus space in stores, as it moves toward a smaller blueprint, led by chief executive Paul Mason.
Somerfield, which was acquired by a consortium including Barclays Capital, Apax and property tycoon Robert Tchenguiz for£1.1 billion last year, already has 250 Tchibo shop-in-shops and 20 Peacocks concessions.
Separately, Robert Dyas chairman and former Somerfield chief executive Alan Smith has stepped down from the board at the Change Capital-backed retailer. Smith is to pursue other business interests. The retailer does not plan to replace him.