This study explored consumer awareness, knowledge and attitudes towards a plant-based diet (PBD) in Belgium, Denmark, the Netherlands and Spain. Furthermore, it assessed knowledge and attitudinal determinants of whether consumers consider the term PBD more appealing than VTD (vegetarian) or VND (vegan). An online survey was conducted among young adults (age 18–30 years) (n = 438) in October 2018. It showed that awareness of the term PBD differed significantly among the countries and was lowest in Spain. Nearly all respondents reported awareness of the terms VTD and VND. Overall, respondents had limited knowledge of a PBD composition and many respondents considered the term PBD equivalent to VND. A neutral to slightly positive attitude towards a PBD was found, and specifically positive regarding health, environment and animal welfare. Many Belgian and Dutch respondents perceived the term PBD as more appealing than VND, while many Danish and Spanish respondents were more indifferent. Knowledge about PBDs and perceiving such diets as tasty and enjoyable contributed significantly to the likelihood of perceiving the term PBD as more appealing than VTD and VND. The concept ‘plant-based diet’ is promising for future health promotion initiatives in Europe, with special focus on provision of adequate information.