In a commercial move, the betting firm will replace accounting company Pinnacle on the Magpies' away shirt for the televised second round tie at Anfield on August 27.
"We have enjoyed some fantastic relationships with high-profile national brands during my time here at Notts County and I am delighted to see that extend further still with the addition of Ladbrokes for this game against Liverpool," said chairman Ray Trew.
"The level of commercial interest that we have had in this fixture shows how big a game it is for the club and I am sure that everyone involved with Notts County is looking forward to our trip up to Anfield, whilst hoping it will be the first of many high-profile fixtures this season and in the years ahead.
"I would like to thank Ladbrokes for their support through this sponsorship, whilst also conveying my appreciation for our season-long sponsors, notably Dave Hodgson and his team at 3663, who are our official home shirt sponsors, and Pinnacle, who sponsor our away shirts this season, as well as Jongleurs Comedy Club, who are our official back of shirt sponsor for the campaign.
"The support of our commercial partners at all levels is invaluable to a club like Notts County and we simply wouldn't be able to achieve our goals without their continued backing."