Interest in healthy living lifestyles has promoted the emergence of many new purported healthy foods, such as microgreens, in the market. Microgreens are young vegetables, different from baby greens and sprouts, harvested ~7-21 days after the cotyledon leaves appeared. However, relatively less is known of the health benefit of microgreens and this warrants further elucidation. Recent advances also indicate modulation of the gut microbiome may contribute to health effects in human. The literature on the effects of kale microgreen as well as mature kale on the gut microbiome remain scarce. In this study, the effects of kale (Darkibor variety) microgreen and its mature counterpart on the gut microbiome were examined to provide science-based information for the emerging new food. Using a mouse model of diet-induced obesity, animals (C57BL mice) were fed with diets contain low fat (10%, LF)) or high fat (45%, HF), supplemented with or without Kale microgreen (KMG) or mature kale (MK) in the perspective diet matrix for 8 weeks. After feeding, cecal content was harvested and subject to 16S rRNA amplicon sequencing followed by bioinformatic analysis. Consumption of KMG and KG significantly attenuated HF diet induced weight gain in mice. Consumption of KMG or MK leads to changes of alpha and beta-diversity in the gut microbiome. However, MK was less effective in modulating the alpha diversity in a low fat matrix. Further analysis also identified as a potential biomarker, an unidentified Ruminococcus species, to be correlated with KMG and MK consumption in both low fat and high matrix. Overall, our results support modulatory effect of consuming kale microgreen on the gut microbiome which appeared to be different from the effects exerted by MK; and diet matrix may also influence manifestation of an effect exerted by vegetables.