We present the results based on dielectric, electro-optical and photoluminescence (PL) measurements of a ferroelectric liquid crystal (FLC) doped with differently functionalised (-COOH, -OH and -NH2 groups) multi-walled carbon nanotubes (MWCNTs). Functional group induced significant modifications in the dielectric permittivity (epsilon '), dielectric loss factor (tan delta), PL intensity and material parameters of MWCNT/FLC composites have been observed. We found that MWCNTs functionalised with -OH and -NH2 have enhanced the dielectric properties and the PL intensity of FLC material remarkably. The observed results have been explained on the basis of the interaction between FLC material and functionalised MWCNTs. The present study is our sincere attempt to understand the effect of functionalisation of MWCNTs on the FLC properties.