Coordinated cell fate determination during the early stages of life is dependent on several key signals. One such class of signals are Wnt proteins, a family of lipid-modified morphogens that play important roles in embryonic development and adult tissue homeostasis. Wnt signalling relies on the palmitoleoylation of a highly conserved serine residue, within a region of structural significance, named the ‘thumb’. This event promotes the engagement of Wnts with the essential proteins that drive their secretion, their transport through the extracellular space and, ultimately, their binding to the receptor. Importantly, mis-regulation of Wnt signalling has been associated with several developmental disorders, cancers and neurodegenerative diseases. However, effective therapeutic strategies aimed at Wnt disorders remain sparse. In this thesis, I aimed to identify novel Wnt interactors through an unbiased interdisciplinary approach, by combining in vivo genetic manipulations in Drosophila with a chemical strategy of covalently trapping palmitoleoyl binding proteins in human tissue culture. Firstly, by expressing a Wnt-biotin ligase (TurboID) fusion protein, either from the endogenous locus of wingless (main Drosophila Wnt) or by overexpression, important regulators of Wingless were identified, together with potential new interactors that were characterised, albeit not extensively. In parallel, lipidated and non-lipidated photoactivatable peptidomimetics of the Wnt ‘thumb’ were designed and synthesised, and shown to colocalise with GPC6, a known Wnt interactor. Engagement of GPC6 with the Wnt peptidomimetics highlighted a new avenue for its potential inhibition, which could have an indirect effect on Wnt signalling. To this end, biophysical and cell-based assays were developed to determine the binding of novel cyclic peptides to GPC6, and how that interrupts Wnt signalling. Together with potential new targets identified from the Drosophila studies, the cyclic peptide binders of GPC6 could become tools for modulating the Wnt pathway, not only deepening our understanding of Wnt, signalling, but also potentially delivering new therapeutic strategies for the treatment of Wnt-driven medical conditions, and providing insight into related signalling pathways.