The Ca2+-calmodulin dependent protein kinase-4 (CaMK4) is the core component of a signalling pathway in neurons that regulates synaptic plasticity, learning and memory. Emerging evidence suggest that the CaMK4 pathway plays an important underlying role in profound forms of autism spectrum disorder, although the mechanisms remain unclear. Little is known about the regulation of CaMK4 or the effector proteins that it engages, leading to its classification as an understudied “dark” kinase. Uncovering the interactome of CaMK4 and generating tools such as small-molecule inhibitors to study its biology, is crucial to understanding how CaMK4 dysregulation leads to neurological disorders. Here, we use biotin proximity-labelling combined with mass spectrometry to map the interactome of CaMK4 and reveal the protein kinase WNK2 as a novel interactor of CaMK4. Furthermore, we expressed and purified milligram quantities of CaMK4 and used a range of biophysical techniques including size-exclusion chromatography, intact mass spectrometry, small-angle X-ray scattering, thermal shift assay and kinase assays to assess its quality for use in a compound library screen. Finally, we performed a screen of a curated kinase inhibitor library and identified four compounds that inhibit CaMK4, which provide important starting points for medicinal chemistry optimisation. Together, these data provide new insights into CaMK4 regulation as well as tools to enable the development of small-molecule inhibitors of CaMK4.