The present investigation reports the nanomechanical properties of electron beam (EB) modified polyamide-6 (PA6) by PF-QNM (PeakForce Quantitative Nanomechanical Mapping) atomic force microscopy (AFM) technique. The samples were irradiated within a selected dose range (25–200 kGy) where branching of PA6 was generated instead of crosslinking. The DMT modulus (based on the Derjaguin-Muller-Toporov model) of PA6 was found to increase (∼131%), whereas, adhesion force (between tip and PA6) and dissipation energy (energy loss) decreased (∼40% and ∼66%, respectively) with increasing dose (25 and 200 kGy). The values of DMT modulus, adhesion force and dissipation energy of EB modified PA6 were in the range of 1.6–3.7 GPa, 75–45 nN and 24–8 keV, respectively. The changes of above properties with dose were correlated to electron-induced branching, restricted segmental mobility and significant reduction of water absorption (∼74% compared to neat PA6). The degree of PA6 branching was predicted from melt rheology studies. Interestingly, crossover frequencies of storage and loss moduli as well as the corresponding phase angle of PA6 were shifted toward lower values with increasing dose. These features indicate the presence of branching and/or micro-gels. The energy loss from AFM was correlated with the phase lag obtained from rheology. This work provides a comprehensive overview and deep understanding of nanomechanical properties and degree of branching of EB modified PA6.