Mr Gurassa is currently BA's director of passenger and cargo business. He had been touted as a successor to Bob Ayling, the airline's chief executive, but was unexpectedly dropped from the inner circle after a shake-up, instigated by Mr Ayling, in September.
In January, he will fill the Thomson role, which was vacated by Paul Brett in July following a gloomy profit warning, and which has since been filled by Roger Burnell, formerly the group's chief operating officer. It is understood that Mr Burnell was "disappointed that he didn't get the job", but will stay on for a few months to ensure a smooth handover. Peter Long, the chief executive of rival First Choice and Mark McCafferty, the head of the Avis car rental group, had also been touted as possible candidates.
It is expected that Mr Gurassa's salary and bonus package will be about pounds 600,000.
Thomson also said yesterday that its non-executive chairman, Michael Brown, would stand down at the group's annual meeting in April.
Shares in Thomson closed up 1p at 93p.