Allen founded successful Australian consumer agency Pulse Communications in 2003, as part of the Ogilvy PR network.
Allen succeeds Barby Siegel who departed Ogilvy last year for a role heading Edelman firm Zeno Group.
In New York, Allen will report to Ogilvy PR global CEO Chris Graves.
'Samantha has the guts and resiliency of an entrepreneur, the professionalism of a world class practice leader, and the creative leaps of imagination of an inventor,' said Graves in a statement.
'She has won some of the top awards in the world for her creative work connecting people and ideas in ways no one else could.'
Prior to founding Pulse, Allen worked in various roles in London and San Francisco, including co-founding full-service agency Chocolate Communications. Under her leadership, Pulse won a string of awards Best New Consultancy at the 2004 Asia-Pacific PR Awards.