In this paper, an approach is proposed to integrate contact-mode imaging with simultaneous broadband nanomechanical property mapping of soft materials in air by using atomic force microscope(AFM). Simultaneous imaging and nanomechanical mapping is needed to correlate the morphological and mechanical evolutions of the sample during the dynamic phenomena such as cell defusion process. However, current method to mechanical property mapping-the force-volume mapping technique-is limited to static elasticity mapping only, whereas the mechanical properties of soft materials are viscoelastic of frequency-dependence in nature. The proposed approach aims to address these challenges to enable simultaneous imaging and broadband nanomechanical mapping of soft materials in air. Specifically, it is proposed to augment a complex excitation input to the sample topography tracking during the imaging process. The proposed approach is illustrated through experimental implementation on a PDMS sample. The experimental results obtained demonstrate that by using the proposed technique, both topography imaging and broadband viscoelasticity quantification can be reliably achieved.