Kazachstania slooffiae is a porcine intestinal yeast whose role in the intestinal environment is largely unexplored. Therefore, the impact of K. slooffiae on growth performance, intestinal microbial metabolites and the microbiota of weaned piglets was investigated in this study. Forty-eight German Landrace pigs were weaned at day 27 or 28 of life and grouped into one control and three treatment groups. During the 5-week experiment, piglets had ad libitum access to feed and water. On days 5, 6 and 7 post weaning, pigs were orally supplemented with either placebo or K. slooffiae cells once a day. Faecal samples collected on days 5–8, 14, 21 and 28 post weaning were used for microbiological and chemical analyses. Between groups, there were no significant differences in the incidence of diarrhoea, pH and growth performance. Total yeasts and K. slooffiae correlated positively with total short-chain fatty acids, acetic, propionic, n-butyric, i-valeric and valeric acids, and negatively with pH. Pyrosequencing of the bacterial intestinal community revealed that K. slooffiae significantly affected the composition of the microbiota. The results of this study suggest that K. slooffiae may play an important role in the porcine digestive system, especially in the critical weaning period.