Rupert Thomas, director of brand development and marketing, said the range was in "double-digit growth and growing faster than the overall Waitrose business".
Essential cornflakes sales were up 17% year-on-year, baked beans 12% and soft cheese 120%, he said. "In some examples, we have taken existing products and rebranded them as Essential and seen fantastic growth," he said.
The retailer is now selling 701 lines of the 1,450-strong product range, which will be fully rolled out in October. Waitrose had lowered the price on a quarter of the products, investing £25m from its own margins, Thomas said.
Research showed many shoppers did top-up rather than full shops at Waitrose, but the Essential range was beginning to change this behaviour, he added. "The very distinctive packaging makes Essential very easy to find," he said. "We knew shoppers were sometimes confused by our range and the clarity of the offer in branches and they wanted to be given the reassurance this was Waitrose quality at prices you wouldn't necessarily expect from us."