Petrella, who joins along with three other appointments to the digital team, will be responsible for leading online creative projects while overseeing a team of eight, working across the agency's roster of clients and driving new business.
He will report directly to Mark Iremonger, Proximity London's head of digital.
Petrella has more than six years' experience in online and multimedia creative design.
Prior to joining Proximity London, he worked at Wheel for more than four years where he became associate creative director.
In this role, he oversaw a department of 25 people and worked on clients including Marks & Spencer, COI and Lloyds TSB.
Proximity London has also appointed Hadleigh Smith and Nicole Redenbach as senior producer and producer respectively. They will be responsible for the production of various client projects.
Smith joins from digital content and media agency Transact Group, while Nicole Redenbach was previously at Leo Burnett Australia.
Mark Hillman joins the agency as copywriter from Syzygy.
Iremonger said: "This is an exciting time for us as we grow our digital offering. I am very pleased with these high-calibre appointments as the quality of our digital team is paramount to our success.
"Their experience will be invaluable in strengthening our integrated offering, which to me means producing great creative ideas that are fluently and seamlessly executed across different media."
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