Dublin-based Glanbia, listed on the Dublin and London Stock Exchanges, hired Hogarth after a three-way pitch process.
Hogarth chief executive Chris Matthews leads the brief with support from a team of two, including associate director Tom Leatherbarrow.
The team reports to Glanbia group director of communications Michael Patten.
'Glanbia's profile has dropped off in the City over the last couple of years while there has been a restructuring process going on and it is only now in a position to start pushing its profile,' said Leatherbarrow.
The brief includes analyst relations work and campaigns targeting financial institutions and the City media.
Patten said: 'Glanbia's position as a leading international food producer is not currently matched by its visibility among investors.'