This paper reports the first investigation of magnetic island-associated beta-induced Alfvén eigenmodes (m-BAEs) in spherical torus, based on the EXL-50 U device. Experimentally, a magnetic island with toroidal/poloidal mode numbers m/n = + 3/−1 is found to drive a pair of m-BAEs at ∼20 kHz. This m-BAE pair propagates in opposite directions, shares the same mode numbers as the island, and exhibits a frequency difference exactly equal to twice the island’s rotation frequency. Under static magnetic conditions, only one m-BAE can be observed, which displays a standing-wave structure with m/n = ± 3/± 1. The standing-wave nodes of the toroidal and poloidal magnetic perturbation from m-BAE, δBθ,m-BAE and δBϕ,m-BAE, are locked near the O-point and X-point of the island. The frequency of the m-BAE (fm-BAE) shows a significant positive linear correlation with the magnetic island width (wisland), and the mode disappears when wisland becomes either too large or too small. Additionally, fm-BAE is also found to be proportional to the Alfvén velocity, consistent with the fundamental characteristics of Alfvén eigenmodes. In short, the experiments on EXL-50 U have systematically brought together the m-BAE features that were previously observed in isolation on different tokamaks. This demonstrates that these features are universal, even in spherical torus. Simulation and calculation of the continuum accumulation point frequency (fcap) is also given in the paper, confirming that experimental fm-BAE falls within the BAE gap at the q = 3 rational surface, and the modes disappear no matter when fm-BAE > fcap. Based on the findings above, the paper further proposes a possible excitation mechanism for m-BAE.