Fumonisin B1 (FB1) is a mycotoxin that mainly contaminates food crops. To avoid the harmful effect of FB1 on the human body, it is necessary to establish a convenient, sensitive, and accurate FB1 detection method. In this study, an optical fiber tip facet biosensor based on the localized surface plasmon resonance (LSPR) that adapts to a general detection platform was developed. An optical fiber end face was assembled with –NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , Au nanoparticles (AuNPs), and aptamer, and the fabricating parameters were optimized. The results showed that the optical fiber LSPR biosensor had a good linear relationship ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}^{\text {2}}$ </tex-math></inline-formula> = 0.9817) between the logarithmic FB1 concentration and the LSPR peak shifts within the linear range of concentrations of 0.8–200.0 ng/mL and a low limit of detection (LOD) of 0.17 ng/mL, as well as selectivity, recovery rates (96.08%–112.23%), and repeatability relative standard deviation (RSD) of 3.37%. It was validated by corn. Therefore, it was feasible that a tip facet optical fiber LSPR biosensor could be used to detect FB1, with advantages of convenience, renewability, and low cost. It is easy to popularize and apply.