An all-optical light–control–light functionality with the structure of a microfiber knot resonator (MKR) coated with tin disulfide (${\mathrm{SnS}}_2$) nanosheets is experimentally demonstrated. The evanescent light in the MKR [with a resonance $Q$ of $～\mathrm{59,000}$ and an extinction ratio (ER) of $～26\mathrm{dB}$] is exploited to enhance light–matter interaction by coating a two-dimensional material ${\mathrm{SnS}}_2$ nanosheet onto it. Thanks to the enhanced light–matter interaction and the strong absorption property of ${\mathrm{SnS}}_2$, the transmitted optical power can be tuned quasi-linearly with an external violet pump light power, where a transmitted optical power variation rate $\mathrm{\Delta }T$ with respect to the violet light power of $～0.22\mathrm{dB}/\mathrm{mW}$ is obtained. In addition, the MKR structure possessing multiple resonances enables a direct experimental demonstration of the relationship between resonance properties (such as $Q$ and ER), and the obtained $\mathrm{\Delta }T$ variation rate with respect to the violet light power. It verifies experimentally that a higher resonance $Q$ and a larger ER can lead to a higher $\mathrm{\Delta }T$ variation rate. In terms of the operating speed, this device runs as fast as $～3.2\mathrm{ms}$. This kind of all-optical light–control–light functional structure may find applications in future all-optical circuitry, handheld fiber sensors, etc.