Town & City Pub Company is introducing half-price soft drinks after 11pm.
It is also selling a range of low-alcohol and alcohol-free beers as part of a responsible retailing drive.
The scheme is being trialled at 14 pubs in north-west England and Scotland, including Glasgow, Liverpool and Barrow-in-Furness.
A spokeswoman for Town & City said: "We are looking to roll it out across the country. It's been very successful."
Dave Daly, manager of Town & City's Castle pub in Blackpool, said the trial is running in its two Yates's bars, the Litten Tree, the Dutton Arms and his pub in the Lancashire seaside resort.
Beers such as 2% abv Carling C2 and alcohol-free Beck's are being stocked as part of the trial.
The tills are all pre-programmed so that all soft drinks prices are automatically halved after 11pm.
Posters carrying a sensible drinking message have been put up inside.
Daly said the move is "working well" in Blackpool, where customers, often holiday-makers, would often drink throughout the day.
"It allows us to make a profit and slow things down a little bit," said Daly.
"It's early days — the trial has only been going for a month — but it's doing a good job."
• Get all the latest pub trade news every day direct to your inbox. Sign-up for our news alerts. Click here.