The controlled one-dimensional supramolecular polymerization of synthetic building blocks in confined spaces constitutes a key challenge to simplify the understanding of the fundamental physical principles behind the behavior of more complex encapsulated polymer networks. Cyclic peptide nanotubes constitute an optimal scaffold for the fabrication of hierarchical one-dimensional self-assembled architectures. Herein we report the pH-controlled nanotube formation and fibrillation of supramolecular cyclic peptides in confined aqueous droplets. The externally triggered self-assembly of these peptides gave rise to viscoelastic hydrogels in which the one-dimensional molecular arrangement was perfectly preserved from the nano- to the micro-scale. The cyclic peptides building blocks were confined inside water microdroplets and the base-triggered supramolecular polymerization was externally triggered and followed by confocal microscopy showing that the confined fibrillation spanned and affected the shape of the droplet micro container.