Dynamic remodelling of the microtubule cytoskeleton and local interactions with intracellular targets are central to many polarized cell biological processes, an idea first formalized as search-and-capture hypothesis three decades ago. However, because of the rapid timescale of microtubule polymerization dynamics, it is difficult to directly ask how, when and where dynamic microtubules participate in specific biological processes. Here, we employ a blue light-sensitive interaction with the oat phototropin LOV2 domain to generate a photo-inactivated variant of the microtubule end-binding protein EB1, a small adaptor that is central to the interaction of functionally and structurally diverse proteins with growing microtubule ends, that can replace endogenous EB1 function. Acute and reversible blue light-mediated π-EB1 photo-dissociation allows spatially and temporally precise control of intracellular microtubule polymerization dynamics. In addition to demonstrating that neither the GTP cap nor the MT polymerase CKAP5 are sufficient to sustain persistent MT polymerization at physiological growth rates, our data illustrate accurate subcellular control of a freely diffusible, cytoplasmic protein at the second and micrometer scale. This novel design may serve as a template for precise control of many other intracellular protein activities.