The airport wants to see the local planning process speeded up to allow its ceiling of 28,000 movements a year to be raised significantly.
But the plans have been opposed by some local residents and last year there was a peaceful protest involving 18 climate change campaigners.
Bell Pottinger's remit is to advise on all aspects of engagement with key political stakeholders and to increase awareness of the airport and the contribution it makes to the UK economy.
The appointment will last for an initial 12 months. The agency previously helped with TAG Farnborough's planning consultation strategy.
The account will be led by associate director Chris Parr, a former aide to former deputy prime minister John Prescott.