The agency will represent LATCB across the UK and Ireland following a pitch in which six agencies were shortlisted.
The brief is described by LUCA as a consumer and travel trade PR contract "to creatively position Los Angeles as a city with endless entertainment options and the premier destination for leisure travel, meetings and conventions".
It will be led by LUCA director Lou Harris, working alongside LATCB teams in both LA itself and London.
Don Skeoch, chief marketing officer for LATCB, said: "2016 is an especially exciting time for Los Angeles, in part because of significant news like the launch of the new direct routes from Manchester and Dublin to LAX. It’s imperative that we have a creative and experienced public relations partner that can continue to position Los Angeles as a must-visit destination in the important market of the UK and Ireland."