Biosecurity is an essential tool for rearing healthy animals. Biosecurity measures (BMs) are well known in poultry production, but it is difficult to assess actual implementation on farms. The aims of this qualitative study were (1) to provide an overview of biosecurity implementation according to poultry farmers in Europe; and (2) to better understand the reported reasons and potential obstacles for not implementing the measures. In seven European Union Member States, 192 farmers (118 under contract with a company and 68 independents) working in seven different categories of poultry production were interviewed on 62 BMs to determine the frequency of implementation and the reasons for non-implementation. Most of the replies (n = 7791) concerning BM implementation were reported by the farmers as “always” implemented (81%), statistically higher for breeders (87%) and layers (82%) and lower for independent farms versus farms under contract with a company (79.5% and 82.5%, respectively). Regardless the poultry production category, the most frequently implemented BMs declared by the farmers were daily surveillance of birds, rodent control and feed storage protection. Standard hygiene practices were also mentioned as high-implementation measures for most production categories, with some deficiencies, such as rendering tank disinfection after each collection and, for meat poultry, disinfection of the feed silo and bacterial control of house cleaning and disinfection between each cycle. The entry of vehicles and individuals onto poultry farms, especially during critical points of eggs collection for breeders and layers, as well as the presence of other animals, such as the “all in/all out” practice, particularly in layers and ducks, were also reported as the least commonly practiced measures. The main reasons for not implementing the measures (n = 1683 replies) were low awareness and poor knowledge of the expected benefits of biosecurity (“no known advantages” 14%, and “not useful” 12%), the lack of training (“not enough training” 5% and “advice” 7%), lack of time (19%), and financial aspects (17%). Despite the good overall biosecurity mentioned by the farmers, these findings highlight certain deficiencies, suggesting room for improvement and the need for targeted and tailored support of poultry farmers in Europe.