The 14-line range features multiple vegan options, including bread, multiple types of vegan mayo, olive oil, and balsamic vinegar.
The chain is expected to launch further products in the supermarket over the next year.
"Finding the right partner to help us take our mission into people's homes was so important," John Vincent, co-founder of LEON, said in a statement sent to Plant Based News.
"Sainsbury's is a supermarket that, like us, puts food and flavor first, so teaming up together just makes sense. Now we're embarking on a partnership that champions food innovation, alongside our values.
"This brand new range is an important step for us as a business as we grow beyond restaurants and continue to live out our ambition to help people access Naturally Fast Food, every day."
Rachel Eyre, Head of Future Brands at Sainsbury's, added: "We are excited to be partnering with LEON to bring their products to the nation's shoppers for the first time, exclusively for Sainsbury's customers.
"At Sainsbury's, we're constantly looking for ways to offer our customers new and innovative products, and LEON's flavor-first philosophy can help us do just that.
"We want to surprise and delight our customers with exciting new products and brands that they can only find in Sainsbury's, and we're confident this exclusive range from LEON will be a hit. This initial range will be followed by further innovation and we will be working closely with LEON and with our customers to decide where to take it next."