Struthiosaurus transylvanicus was named by Nopcsa (1915). Its type specimen is BMNH R4966, a partial skeleton, and it is a 3D body fossil. Its type locality is Szentpéterfalva, Hateg Basin, which is in a Maastrichtian fluvial sandstone in the Sânpetru Formation of Romania. It was considered monophyletic by Vickaryous et al. (2004).

It was corrected as Struthiosaurus transsylvanicus by Nopcsa (1929); it was synonymized subjectively with Struthiosaurus austriacus by Pereda-Suberbiola and Galton (1992) and Pereda-Suberbiola and Galton (1994); it was misspelled as Struthiosaurus transsylvanicus by Lapparent (1947), Mamulea (1953), Jeletzky (1960), Kuhn (1964), Simmons (1965), Charig (1967), Dinca et al. (1971), Coombs (1978), Molnar (1980), Jurcsák (1982), Grigorescu (1984), Pereda Suberbiola and Galton (1997), Ford (2000), Vickaryous et al. (2001), Carpenter (2001), Pereda Suberbiola and Galton (2001), Grigorescu (2003), Vickaryous et al. (2004), Grigorescu (2004), Grigorescu (2005), Bojar et al. (2005), Dalla Vecchia (2006), Pereda Suberbiola and Galton (2007), Pereda Suberbiola and Galton (2007), Osi and Makádi (2009), Parsons and Parsons (2009), Weishampel et al. (2010), Codrea et al. (2010), Grigorescu (2010), Stanford et al. (2011), Ösi and Prondvai (2013), Brusatte et al. (2013), Kirkland et al. (2013), Kineer et al. (2016) and Pérez-Pueyo et al. (2021).