Hogg Robinson is headquartered in London, and had revenues of £318.3m in 2016. It owns expenses and travel technology provider Fraedom, and business travel and data management firm HRG.
FTI began working with Hogg Robinson this month, with the account being handled by a UK-based team that includes FTI Consulting senior managing director John Waples. Managing directors Elspeth Rothwell and Matthew O'Keeffe will also work on the account, alongside director Alex Le May.
Hogg Robinson group chief executive David Radcliffe said the appointment of FTI was an "important part" of the company's evolution.
Earlier this week, FTSE 100 private healthcare group Mediclinic announced that it had also appointed FTI Consulting as its retained financial communications adviser.
FTI Consulting is headquartered in Washington, DC and is listed on the New York Stock Exchange, with equity market capitalisation of $1.4 billion (£1.1bn). Its Strategic Communications business, with 2015 revenues of $189m, is ranked by PRWeek's Global Agency Business Report as the world's 14th largest PR firm.