Collapsed fast grocery delivery service Milkrun has been rescued by industry giant Woolworths.

The company emailed customers on Thursday, announcing it would now be branded Milkrun powered by Metro.

Supplied by Woolworths Metro, the takeover sees Milkrun and its blue branding become a part of the grocery chain's Metro60 platform.

Delivery is expected to average 33 minutes, with no service fee and a flat $5 delivery charge.

The ultra-fast start-up built its brand on cheap prices and an initial promise of 10-minute delivery.

But it made the decision to close in April because of financial troubles.