Yes. Humans are synapsids. Synapsida is one of the two major amniote lineages on the tetrapod tree; living mammals—including monotremes, marsupials, and placental mammals such as humans—are the extant representatives of that clade.
A hallmark of synapsids is a single temporal opening (fenestra) in the skull behind the eye socket, where jaw muscles attach. The Field Museum illustrates that same opening on a human skull alongside early synapsids such as Dimetrodon, underscoring that mammals sit inside Synapsida rather than among reptiles.
Source: Field Museum — The Fossil Non-mammalian Synapsid Collection