Isobel won the bingo club operator's business after a competitive pitch against BMB, Fold7 and George & Dragon in a process handled by AAR.
Gala Leisure was bought for £241m by private equity company Caledonia Investments from Ladbrokes Coral in 2015 and is gearing up for a relaunch later this year, which could reportedly mean a renaming of the brand to Buzz Bingo.
The Twitter handle @GalaBuzzBingo is currently dormant despite being registered to the social media platform in September 2013.
The brand has been hit by consumers' move towards online gambling. Because its brand websites galabingo.com and galacasino.com are still owned by Ladbrokes Coral, Gala Leisure could rebrand the Gala Bingo name for its clubs as part of an online push.
Newcastle-based agency Cravens will continue to hold the Gala Bingo online account since winning the business in 2014, while there was no agency incumbent for Gala's leisure clubs.
Isobel will be responsible for all creative comms, including advertising, content and social, as well as contributing to internal comms.
Caledonia was also reportedly seeking to offload some of its Gala Bingo halls last year in a bid to improve profits.
Nottingham-headquartered Gala Leisure reported a profit of £18.1m in its latest financial accounts from 27 September 2015 to 4 January 2017, compared to a £10.2m loss during the 12 months to 26 September 2016.
Andy Goram, the long-serving marketing director who joined Gala Coral Group in 2006, was promoted last year to the expanded role of chief brand experience officer.
He said: "2018 is going to be an exciting year for us as a business and we are delighted to be working with Isobel. It was a hard-fought pitch but in the end Isobel’s understanding of our business shone through in all the work."
Mecca Bingo, Gala’s high-street rival, appointed Pablo as its creative agency in 2016.