Bioactive polymeric scaffolds are a prerequisite for the ultimate formation of functional tissues. Here, we show that supramolecular polymers based on quadruple hydrogen bonding ureido- pyrimidinone ( UPy) moieties are eminently suitable for producing such bioactive materials owing to their low- temperature processability, favourable degradation and biocompatible behaviour. Particularly, the reversible nature of the hydrogen bonds allows for a modular approach to gaining control over cellular behaviour and activity both in vitro and in vivo. Bioactive materials are obtained by simply mixing UPy-functionalized polymers with UPy- modified biomolecules. Low- molecular- weight bis- UPy- oligocaprolactones with cell adhesion promoting UPy- Gly- Arg- Gly- Asp- Ser ( UPy-GRGDS) and the synergistic UPy- Pro- His- Ser- Arg- Asn ( UPy- PHSRN) peptide sequences are synthesized and studied. The in vitro results indicate strong and specific cell binding of fibroblasts to the UPy- functionalized bioactive materials containing both UPy- peptides. An even more striking effect is seen in vivo where the formation of single giant cells at the interface between bioactive material and tissue is triggered.