Camarasaurus was named by Cope (1877). It is the type genus of Camarasauridae, Camarasaurinae.

It was assigned to Cetiosauridae by Cope (1891) and Cope (1898); to Atlantosauridae by Sauvage (1882), Dollo (1884), Nopcsa (1901) and Hay (1902); to Opisthocoelia by Osborn and Mook (1919); to Sauropoda by Williston (1878), Seeley (1879) and Joleaud (1922); to Morosauridae by Zittel (1890), Marsh (1895), Marsh (1896), Marsh (1898), Huene (1908), Huene (1908), Huene (1909), von Zittel (1911), Lull (1924), Huene (1927), Huene (1927) and Huene (1929); to Brachiosauridae by Tatarinov (1964) and Romer (1966); to Titanosauridae by Madsen and Miller (1979); to Camarasaurinae by Nopcsa (1928), Romer (1956), Steel (1970), Swinton (1970), Coombs and Molnar (1981) and McIntosh (1990); to Brachiosauria by Upchurch (1997); to Camarasauromorpha by Royo-Torres et al. (2006) and Sekiya (2011); to Eusauropoda by Upchurch et al. (2007) and Apaldetti et al. (2013); to Macronaria by Sereno (1997), Sereno (1998), Wilson and Sereno (1998), Sereno (1999), Sereno et al. (1999), Smith et al. (2001), Wilson (2002), Apesteguía (2005), Apesteguía (2005), Gallina and Apesteguía (2005), Allain and Aquesbi (2008), Suteethorn et al. (2010), Ksepka and Norell (2010), Canudo et al. (2010), Whitlock (2011), D'Emic (2012) and Xing et al. (2015); and to Camarasauridae by Cope (1877), Cope (1878), Cope (1878), Hay (1930), Lapparent (1943), Galton (1977), McIntosh (1981), Santafé et al. (1982), Rich et al. (1983), Russell (1984), Bonaparte (1986), Sanz (1986), Bonaparte (1986), Carroll (1988), McIntosh (1990), Miller et al. (1991), Mcintosh et al. (1992), Hunt and Lucas (1993), Carpenter and McIntosh (1994), Upchurch (1995), Upchurch (1995), McIntosh et al. (1996), McIntosh et al. (1996), McIntosh (1997), Dodson (1997), Dong (1998), Bonaparte (1999), Upchurch et al. (2004), Ikejiri (2005), Foster (2005), Chure et al. (2006), Moser et al. (2006), Mocho et al. (2014), Foster and Peterson (2016) and Mannion et al. (2019).