Chief executive Trevor Bish-Jones said Worth It is on course to become a£100 million brand within 18 months.
Worth It sales averaged between£2 million and£3 million a week in December.
The brand will be extended into more categories in expectation of ongoing appeal to consumers worried by financial uncertainty.
Despite Worth It’s success, like-for-like sales at Woolworths’ core retail division fell 3.2 per cent in the 49 weeks to January 12.
Bish-Jones said he could have adopted a high risk Christmas strategy of only driving sales, but decided to “hunker down”.
He said: “We had thumping-good cost control and de-risked, because we were mindful that consumer confidence wouldn’t be high.”