Healthy diet and dietary diversity have been associated with healthy ageing. Several scores have been developed to assess dietary diversity or healthy diets in epidemiological studies, but they are not adapted to be used in the context of preventive nutrition interventions. This study aimed to develop an occurrence-based healthy dietary diversity (ORCHID) score easy to implement in the field and to validate it using dietary data from older participants in the latest French food consumption survey (INCA3). The ORCHID score was made of several components representing the consumption occurrences of twenty food groups, in line with French dietary guidelines. The score was then validated using dietary data (namely three 24-h recalls and a food propensity questionnaire) from 696 participants aged 60 years and over in the INCA3 survey. Score validity was evaluated by describing the association of the score with its components, as well as with energy intakes, solid energy density (SED) and the probability of adequate nutrient intakes (assessed by the PANDiet). Higher scores were associated with more points in healthy components such as 'fruits' and 'vegetables' (r = 0•51, and r = 0•54, respectively). The score was positively associated with the PANDiet (r = 0•43) and inversely associated with SED (r = −0•37), while no significant association was found with energy intakes. The ORCHID score was validated as a good proxy of the nutritional quality of French older adults' diets. It could therefore be a useful tool for both public health research and nutrition interventions.