Nanopores can be used to detect and analyse biomolecules. However, controlling the translocation speed of molecules through a pore is difficult, which limits the wider application of these sensors. Here, we show that low-power visible light can be used to control surface charge in solid-state nanopores and can influence the translocation dynamics of DNA and proteins. We find that laser light precisely focused at a nanopore can induce reversible negative surface charge densities as high as 1 C m(-2), and that the effect is tunable on submillisecond timescales by adjusting the photon density. By modulating the surface charge, we can control the amount of electroosmotic flow through the nanopore, which affects the speed of translocating biomolecules. In particular, a few milliwatts of green light can reduce the translocation speed of double-stranded DNA by more than an order of magnitude and the translocation speed of small globular proteins such as ubiquitin by more than two orders of magnitude. The laser light can also be used to unclog blocked pores. Finally, we discuss a mechanism to account for the observed optoelectronic phenomenon.