Perry has served as a non-executive director at The Fourth Angel since last March.
in a 20-year career in media and publishing she has held several senior commercial and strategy roles, including stints at Asos, AOL, Emap and the Express Newspaper Group.
Moxham said Perry’s appointment follows "a number of significant account wins", including organic snacking brand Organix.
Last year The Fourth Angel hired directors Becky Westaway – who previously held roles at Avon Cosmetics, Hill+Knowlton, Badger Communications and 3 Monkeys Zeno – and Julia Devonshire, who previously worked as an associate director at Porter Novelli and FleishmanHillard Fishburn.
"It’s been a pretty full-on 18 months, but we’ve been focused on managed growth and really nailing our authentic proposition," Moxham said.
"It’s clear we’re a disruptive challenger consultancy offering integrated new-age comms born out of PR. For that reason I wanted an MD from a left-field background."
She added: "With Sarah’s proven success across diverse media, coupled with her commercial acumen, this experience and expertise gives us a fresh offer and perspective few other traditional PR agencies are currently offering."
Perry said: "After over 20 years working in some of the UK’s biggest media houses… being asked to come on board to scale and shape this business is proving the most exciting challenge yet. To work alongside such an inspirational leader and industry legend as Angie Moxham meant that taking this role was an absolute no-brainer."
The Fourth Angel has also joined the Globalcom PR Network and built strategic partnerships with global creative advisory network Background Creative Counsel, IE Music & Entertainment, and specialist strategic content consultancy Missile Digital, which is owned by the former chief executive of Ten Alps, Alex Connock.