An ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the simultaneous quantitative determination of fumonisin B₁ (FB₁), fumonisin B₂ (FB₂) and fumonisin B₃ (FB₃) residues in milk powder and milk has been established. The samples were extracted with methanol-acetic acid (98:2, V/V), diluted, cleaned up by immunoaffinity chromatography (IAC), and blown to dryness under nitrogen. The residue was re-dissolved and detected using an electrospray ionization source (EIS) in the positive ion mode with multiple reaction monitoring (MRM)and quantitative analysis was performed by the isotope-labeled internal standard method. The limit of quantification was 10 μg/kg for FB₁, FB₂ and FB₃ in milk powder and milk. The recoveries at spiked concentration levels of 10–400 μg/kg were 92.8%–107.5%, with relative standard deviations (RSD) of 2.0%–4.3%. The matrix effects were 96.25%–122.84%. This method was characterized by short analysis time and was suitable for the determination of fumonisin residues in different dairy products.