With up to 900 pubs in the running to take part, the aim is to encourage footfall and sales in the venues.
The offer runs from 16 to 29 May and will be offered to pubs that sell Stella or Carling and show live sport.
Stephen Martin, category manager for Punch, said he wanted to raise awareness of the participating pubs in the community - and there will be support on social media.
In order to receive their free pint, all customers have to do is visit www.freedrinkpubs.co.uk and search for their local Punch pub.
They then redeem the voucher and hand over the bar.
Martin added: “The interest from our publicans so far has been really encouraging and demonstrates their forward-thinking entrepreneurial skills.
“This promotion is a useful tool for publicans to engage with their local community and attract new customers.
“The timing of this promotion also complements the business-end of the sporting season so we see this going down particularly well with sports fans; whether they’re celebrating or commiserating!”