SSP said it has now started a search for a successor for Mr Smith, who joined the group in 2014.
The boss of Upper Crust owner SSP Group has said he will be stepping down at the end of the year.
Simon Smith chief executive of the food service business, confirmed he is leaving the role for a new opportunity at an unnamed private equity-backed business.
SSP, which also operates the Ritazza coffee shops brand, said he is expected to go at the end of 2021 and will continue with his existing responsibilities and support an orderly transition in the intervening period.
The group said it has now started a search for a successor for Mr Smith, who joined the group in 2014 as head of its UK and Ireland business, before becoming chief executive in 2019.
His tenure at the London-listed company has coincided with its most challenging trading period after its railway station and airport sites were hammered by the pandemic and ensuing restrictions.
The group cut around 5,000 jobs last year following the impact of the first lockdown.
SSP told shareholders on Wednesday that it has begun to see a recovery in passenger demand, led by domestic and leisure travel, most notably in North America over recent months.
Current trading is in line with expectations, with the latest week at 42% of pre-pandemic levels from 2019.
Chairman Mike Clasper said: “Throughout the past 16 months, Simon and our executive team have done an excellent job in steering SSP through the enormous challenges presented by the pandemic, acting very rapidly to protect the business and its cash flow, create a more flexible operating model and strengthen the balance sheet.
“SSP has a very clear strategy and significant competitive strengths, placing it in an excellent position to take advantage of the many opportunities for growth that will be presented by the recovery in the travel sector.”
Shares in SSP were 3.6% lower at 254.8p in early trading on Wednesday.