The potential of brewers’ spent grain (BSG) as a functional food ingredient has been investigated for having high nutritional value. A high amount of dietary fiber of BSG shows a high ability to bind water; thus, it tends to solidify food mixture. This characteristic has a beneficial effect in the utilization of BSG as a filler and texturizer in yogurt. The study aims to evaluate the impact of the BSG addition in yogurt production and its quality. BSG was prepared in three different particle sizes, and an amount of 10% was added for yogurt fermentation. The impact of BSG addition was evaluated after 24 h of storage. The result shows that different particle sizes of BSG had no significant impact on pH and syneresis, while it significantly affected the amount of lactic acid and countable S. thermophilus. However, BSG increased the fermentation rate of yogurt, and had a positive impact on water holding capacity. A lower particle size had a higher amount of lactic acid and a lower S. thermophilus. The lower particle size lowered the lightness of the yogurt. Rheological analysis showed that a higher particle size of BSG increased the shear stress and viscosity of yogurt.