The retailer will not be named until it launches its online business "in order to retain competitive advantage", Ocado said.
Ocado will provide the retailer with its software platform, expertise, and support services to help it create "an efficient and intelligent online grocery business", it said.
Orders will initially be fulfilled from the retailer's manually operated centralised warehouse. However, the contract gives the retailer the right to request that fully automated mechanical handling equipment be installed in future in centralised warehouses powered by Ocado's platform, it said.
An upfront fee will be followed by ongoing fees based on the volume of products sold online.
Tim Steiner, chief executive of Ocado, said: "We are delighted that our partner has decided to adopt OSP for its online operations. This is an exciting step in the evolution of our business and in the delivery of our strategy."
"As this particular retailer looks to develop its online offering the agreement we have signed provides the flexibility to expand its capacity efficiently in the future," he said.
Ocado began commercialising its intellectual property in 2013 with an agreement to operate the online business of Wm Morrison Supermarkets in the UK. This agreement was further expanded in 2016, it said.