The foodservice wholesaler is the largest company to join Landmark in the past eight years and becomes its second-largest foodservice member, with the top spot held by DBC. It will also become Landmark's fourth-largest member overall.
JJ has never sold alcohol but would use the buying group's power to move into the sector, it said.
"We chose Landmark because of its full and comprehensive licensed and grocery offering, and its commitment to the future of the foodservice and catering sector," said CEO Mustafa Kiamil. "We felt that Landmark Wholesale's professionalism and the way it conducts its business fitted most closely to our own."
JJ Food Service was 26th in The Grocer's Big 30 Wholesaler ranking, published earlier this month. Its turnover rose 5.1% to £134.4m in the year to March 2010, spurred by the opening of new depots and take up of its click and collect cash & carry offering.
Although profits slumped by 43.4% to £5m which JJ said was an inevitable consequence of price-cutting initiatives to support customers its 3.7% pre-tax profit margin is more than treble the industry average. It has six depots and is in talks to open further sites in Bristol and Glasgow this year.
The additional buying power of its new member virtually cancelled out the impact of losing four members last year, said MD Martin Williams. "JJ's joining reflects the efforts we have made to develop our catering and foodservice business," he added. "They share our future vision."
JJ is the sixth wholesaler to join Landmark in the past nine months. Sales at Landmark depots are up 10% year-on-year, with own label licensed sales up by 30%, he added.
Booker CEO and The Grocer's guest editor Charles Wilson described JJ Food Service as a "great business."