He assumes full responsibility for the clients, employees, and the growth and direction of the UK consumer tech PR specialist agency, the agency said.
George (pictured) will also work with the French and German businesses to deliver "pan-European, multi-disciplinary campaigns" and support "further multi-market opportunities".
George, who reports to group MD Pietro Ranieri, joined from Lewis Communications, where he was UK head of consumer. He has also worked at Brando (now Citizen) and Porter Novelli.
Majority ownership is held by Pietro Ranieri, who founded the agency in 2002. The minority shareholder is Avinity, which also owns stakes in social media marketing specialist Momentum Social, creative digital agency Nonsense, engagement agency Extonare and pre-pay and digital reward agency Intelligent Card Solutions.
The agency said at the time it was targeting acquisitions across the continent.
Clients added to the roster since George's arrival include Ava, BuddahTek, CodeCheck, eBuyNow (Moto Watches & Kodak), Happiest Baby Company, Firexo, LIFX and IAG.
Pietro Ranieri said: "[George] has built a stellar portfolio of experience working at top communications agencies.
"As the Ranieri Agency grows, it has to continue to employ people who add value and proactivity, which Ranj does in buckets. Initially a consultant with us, it became clear to me straight away that I wanted him running my UK agency, which is built as much upon expertise and ethos as it is with the creative diversity of the people I employ.
"We get on extremely well and I only have admiration and respect for his talent, work ethic, as well as the breadth of his experience. Ranj will play a pivotal role in helping to shape the growth plans across all our territories."
George said: "I want to change the status quo of what agencies sometimes preach as their raison d’etre and shop-front, juxtaposed with the smoke and mirrors of what really happens internally.
"Ranieri Agency is nimble enough to constantly evolve, adapt, learn and make a tangible difference to client needs so they are always placed front and centre. Here, there is the ambition and scale of a multi-market household name agency, whilst providing a boutique-style agency client experience."
The Raneri Agency's UK revenue grew 29 per cent in 2018 to reach £1.9m, employing 16 people in the country at the year end, according to the PRWeek UK Top 150 Consultancies table.