This study was made to investigate the long-term effects of different floor housing systems on the welfare of fast-growing broilers. The experiment was performed on 210-day-old fast-growing hybrid male chickens with identical conditions until 47 days of age. Animal-based welfare parameters were measured to investigate the welfare level in the group housed on deep litter, a litter and slat system, and a slatted floor, with five replicates for each group. Results showed that the main welfare indicators in live birds, such breast dirtiness, plumage score, footpad lesion, and hock burn lesion, were negatively affected in broilers kept on conventional deep-litter floor housing. But hemorrhage or lesion scores of the breast and shoulder of broilers in slat floor housing were found to be significantly greater than in conventional deep litter as a result of a heavy body weight at a greater slaughter age (p < 0.05). Pathologically, the prevalence of footpad and hock joint dermatitis was very high in the deep-litter housing system. Femoral head necrosis was not observed in any floor housing group. The results indicated that keeping broilers on a slat flooring system is preferable for younger slaughter ages and for a lighter slaughter weight. When considering the relationship between animal welfare and production economy, moving from one floor house system to another floor housing system should be carefully weighted in future decisions. Moreover, further investigations are needed in order to examine the incidence of joint and bone problems with muscle inflammation in heavier broilers in commercial conditions.