Application of micrometre-scale konjac gel as fat analogue in mayonnaise was studied. Three concentrations of konjac glucomannan (KGM) were applied to prepare micronized konjac gel. The best combination of fat analogue used in mayonnaise was 4.0 wt% konjac glucomannan and 0.36 wt% sodium carbonate. Then fat was partially substituted by micrometre-scale konjac gel at levels of 10, 20, 30, 40, 50, and 60% which were referred to as R10, R20, R30, R40, R50, or R60 formulations, respectively while the full fat (R0) mayonnaise without konjac gel substitution was used as a control experiment. The effects of substitution ratio was determined by rheology measurements, colour measurements, optical microscope observation and caloric values analysis which indicated that fat in mayonnaises substituted with konjac gel of not more than 30% was acceptable. At the meanwhile, the product has good storage stability in a certain storage period. This study shows good potential for spent micronized konjac gel to be used as a fat analogue in mayonnaise.