Human Frizzled-1 (FZD1) is a seven-transmembrane receptor protein belonging to the Frizzled family of Wnt receptors, which includes FZD1–FZD10 that mediate signaling in the Wnt signaling pathway. In humans (Homo sapiens), FZD1 is expressed in a variety of tissues including bone, brain, and other epithelial and connective tissues, where it functions as a cell-surface receptor for Wnt ligands. Upon binding of Wnt proteins, FZD1 interacts with co-receptors such as LRP5/6 to activate downstream signaling pathways, most notably the canonical Wnt/β-catenin pathway, as well as non-canonical Wnt signaling pathways. These signaling cascades regulate cell proliferation, differentiation, migration, and tissue development. In human physiology, FZD1 plays an important role in bone formation and osteoblast differentiation, contributing to the regulation of skeletal development and bone remodeling. Dysregulation of Wnt–FZD1 signaling has been associated with cancer, bone disorders, and developmental abnormalities, as aberrant activation of Wnt signaling can lead to uncontrolled cell growth and altered tissue homeostasis. Consequently, human FZD1 is widely studied in developmental biology, cancer research, and regenerative medicine as a key component of the Wnt signaling network controlling cell fate and tissue maintenance.