The utility group has become the latest company to be part of the loyalty programme, joining the likes of Sainsbury's and American Express.
British Gas will replace EDF Energy next year, ending a seven-year association.
As part of the deal, British Gas will offer its customers several ways of collecting rewards points and benefitting from being part of the programme.
These include – together with money off at retailers – tickets for Eurostar and Vue cinema.
The deal kicks off early next year, when further details of the scheme will be announced.
Benefits will also be attained by customers switching to direct debit or paperless billing, as well as for taking up additional services.