Katz, who was MD of digital at Edelman in London, will join Fishburn in the new role of chief client & operations officer in the same month Pendry is set to take up his position as MD of corporate.
The appointments follow the merger in January of Fishburn’s corporate, consumer, digital, brand and reporting businesses, comprising Fishburn Hedges, 77 and Further.
Katz, who will report to Fishburn chief executive Ali Gee, will be responsible for making sure the agency lives up to its Think Connected truly integrated campaign proposition.
Gee said: "Part of Leah’s role is to make sure that we are set up as an agency to think in an integrated way. The intention is that she will be able to guide all of us in the creation of campaigns that are not siloed by discipline.
"We are focused on making sure all of our campaigns are founded in proper, up-to-date research, which is the basis for the strategy; that informs the creation of a single big idea that can play out across all channels, which we think will be important through our planning intelligence."
Gee added that there was at least one more senior role that needed to be filled but said that there was a shortage of people with the right mix of experience across corporate, consumer, digital and social.
"We need the leadership to be able to work fluidly across digital, PR, social and all other disciplines and there are surprisingly few people who are as fluent in social media as they are in PR," she said.
Gee said Katz, who in her former role led a team of 90 social and digital specialists and managed some of the world’s largest social communities, was one of those few and it was her blend of expertise across digital, social and PR – gained in-house and agency side throughout her career – that made her the right choice for Fishburn’s leadership team.
Katz said: "With the lines blurring between the communications disciplines, it is more important than ever for agencies to break their own silos and produce truly integrated thinking. I'm thrilled to be joining an agency with such commitment to this and excited to be part of the leadership team driving this thinking."
Edelman has not yet commented on Katz's departure.