The development of biomaterials and engineered tissues are reshaping the future of medicine. Soft and injectable materials are increasingly used to treat pathologies, release drugs and/or seed cells for tissue engineering. Mechanical properties of a biomaterial are critical for its functional efficiency. However, the non-destructive mechanical characterization of soft biomaterials, especially in presence of cells, is still a challenge. The aim of this work was to validate the use of a new instrument, ElastoSens™ Bio2 (Rheolution Inc., Montréal, QC), that measures in real-time, nondestructively and without contact the evolution of rheological properties of viscoelastic biomaterials during reticulation kinetics and tissue culture. This study introduces this new technology and compares it with classical rheometry. The gelation kinetic of various hydrogels was studied by both techniques in parallel. The cytocompatibility of the instrument’s sample-holder was verified. Finally, preliminary results of viscoelastic measurements performed on a three-dimensional culture of fibroblasts in hydrogels during culture period are presented.