The objective of this study is to investigate the utility of gelatin hydrogel-fragmented fibers (GHFF) as a material to suppress the shrinkage of cell sheets, which often happens upon detaching from a culture plate. The GHFF were fabricated by cutting gelatin hydrogel nonwoven fabrics. MC3T3-E1 cells were simply mixed with different amounts of GHFF, followed by culturing to formulate the cell sheet homogeneously incorporating GHFF. When detached from the culture plate, the cell sheet formulated without GHFF shrunk while the area became about 23% of the original one before detachment. On the contrary, the cell sheet formulated with GHFF hardly shrunk. The lactate/glucose ratio of a metabolic activity was significantly lower and the adenosine triphosphate (ATP) production was higher for the cell sheet formulated with the GHFF than that obtained without the GHFF. An osteogenic activity was high for the cell sheet formulated with the GHFF compared with that obtained without the GHFF. The GHFF addition was a simple and promising method to fabricate active cell sheets without size change. Impact Statement This study introduces the utility of gelatin hydrogel-fragmented fibers (GHFF) for cell sheet engineering. Upon detaching from the culture plate, the cell sheet formulated without GHFF shrunk, while the area became about 23% of the original one before detachment. On the contrary, the cell sheet formulated with GHFF hardly shrunk. The GHFF allowed cell sheets to enhance the metabolic and osteogenic activities. The GHFF addition was a simple and promising method to fabricate active cell sheets without size change.