This article presents the correlation of creep and viscoelastic properties to the cytoskeletal structure of both tumorigenic and non‐tumorigenic cells. Unique shear assay and strain mapping techniques were used to study the creep and viscoelastic properties of single non‐tumorigenic and tumorigenic cells. At least 20 individual cells, three locations per cell, were studied. From the results, lower densities in the volume of actin, and keratin 18 structures were observed with the progression of cancer and were correlated to the increased creep rates and reduced mechanical properties (Young's moduli and viscosities) of tumorigenic (MDA‐MB‐231) cells. The study reveals significant differences between the creep and viscoelastic properties of non‐tumorigenic breast cells versus tumorigenic cells. The variations in the creep strain rates are shown to be well characterized by lognormal distributions, while the statistical variations in the viscoelastic properties are well‐described by normal distributions. The implications of the results are discussed for the study of discrete cell behaviors, strain and viscoelastic responses of the cell, and the role of cell cytoskeleton in the onset and progression of cancers.