Titanium (Ti)–niobium (Nb) thin alloy films were prepared by on-chip sputtering. Their surface properties were characterized, and their cell growth and adhesion properties were investigated. Protrusions were observed on the surface of a thin film made of Ti mixed with a small amount of Nb; these protrusions were smaller and more numerous than those on Ti and Nb thin films. Addition of a small amount of Nb enhanced cell adhesion and cell growth compared to those of Ti or Nb thin films. In addition, cell growth and adhesion decreased with an increase in Nb content. Therefore, the stable morphology, negative zeta potential and suitable protrusion size of these Ti–Nb thin alloy films enhance cell adhesion and cell growth on their surfaces.