The maxilla begins developing during the fifth week of embryonic life from the first pharyngeal (or branchial) arch, which also gives rise to the mandible and other facial structures. Development is initiated by the formation of mesenchymal condensations in the region of the primitive stomodeum (future oral cavity). These cells differentiate under the influence of various signalling proteins, such as sonic hedgehog (SHH), bone morphogenetic proteins (BMPs), and fibroblast growth factors (FGFs).

By the seventh week of gestation, the maxillary processes fuse with the medial nasal prominences to form the upper lip and anterior maxilla. Meanwhile, the palatal shelves, extensions of the maxillary processes, grow medially and fuse to form the hard palate. This fusion completes by the 10th week of gestation, leading to the separation of the oral and nasal cavities.