Seed maturation is an important process that is evolutionarily advantageous, allowing for seed dispersal and germination under favourable growth conditions. The B3-domain transcription factor FUSCA3 (FUS3) is a master regulator of seed maturation and controls developmental phase transitions through hormonal regulation in Arabidopsis thaliana. The aim of this study was to determine the post-translational regulation of FUS3 during embryonic and vegetative development. Here, FUS3 was found to interact with the E3 ubiquitin ligase ABI3-INTERACTING PROTEIN2 (AIP2) in yeast two-hybrid, in vitro, and in planta assays. Analysis of transcriptional and translational reporters also showed overlapping spatial and temporal expression patterns of AIP2 and FUS3. Furthermore, in vitro FUS3 degradation was delayed in aip2-1 mutant and increased FUS3-GFP levels were observed during mid-embryogenesis in aip2-1. Finally, double transgenic plants overexpressing AIP2 and FUS3 showed reduced FUS3 levels and reversion of the gain-of-function FUS3 phenotypes back to WT. Together, these results indicate that AIP2 is a negative regulator of FUS3.