In this study, stimulus objects (frozen blood balls, fresh zebra dung, scented squash, and cardboard boxes) were utilized in an enrichment program aimed to increase the diversity of behaviors exhibited by one female and three male tigers (Panthera tigris sumatrae) and two male lions (Panthera leo leo). Three enrichment sessions consisting of pre-enrichment control, enrichment, and post-enrichment trials of 30-min each were conducted over a two-day period. Stimulus objects were present only in the enrichment trials. The enrichment sessions were replicated three times for each stimulus object. Behavioral states, discrete behaviors, and object-directed behaviors were recorded. Behavioral diversity indices (BDIs) for each trial were calculated using the Shannon Diversity Index. The stimulus objects increased behavioral diversity during the enrichment trials compared to the control trials, but this effect did not persist to the post-enrichment trials the following day. The lions benefited the most from the enrichment, exhibiting increased activity, decreased sleeping, and the greatest increase in discrete behaviors BDIs during the enrichment trials. The type of stimulus object did not affect behavioral states or discrete behaviors BDIs, but the frozen blood balls elicited lower object-directed BDIs than other stimulus objects. Responses to enrichment did not change over time, suggesting that the subjects did not habituate to the stimulus objects during the 10 weeks of the study. Enrichment utilizing stimulus objects was successful in increasing behavioral diversity of lion and tiger subjects. Differences in the study among subjects in their response to enrichment suggest that the effects of enrichment on animals of different age, sex, and species should be further explored and taken into consideration in the design of enrichment programs.