The aim of this study was to evaluate the aqueous extracts of sweet passion fruit (Passiflora alata), araçá (Psidium cattleianum), rosemary (Rosmarinus officinalis) and oregano (Origanum vulgare) for their ability to degrade aflatoxin B1 (AFB1) in vitro. The AFB1 levels in decontamination assays (16.67 ng mL−1) were measured by high performance liquid chromatography after incubation periods of 12, 24, 36 or 48 h at 37 °C. Degradation rates were compared to controls (mycotoxins in water) under the same incubation conditions. The ability to reduce the levels of zearalenone (ZEN) and ochratoxin A (OTA) was also tested, although no significant degradation was observed for any extract tested. A time-dependent decrease in AFB1 levels was observed in the aqueous leave extracts of all plants. Rosemary extract had the highest (P < 0.05) percentage of AFB1 reduction, with mean percentages of 49.0 ± 5.6% to 60.3 ± 2.9% at 24–48 h, followed by oregano after 48 h of incubation (38.3 ± 4.6%) and araçá at 36 h (30.7 ± 3.8%). These results demonstrated that plant extracts are interesting alternatives for the control of aflatoxins in food substrates, although further studies are needed to assess the toxicity of the resulting compounds from degradation.