Plioplatecarpus was named by Dollo (1882) [Sepkoski's age data: K Camp-u K Maes-l Sepkoski's reference number: 1069]. It is not extant. It was considered monophyletic by Cuthbertson et al. (2007).

It was assigned to Squamata by Sepkoski (2002); to Mosasauridae by McDowell and Bogert (1954), Carroll (1988) and Novas et al. (2002); to Russellosaurina by Bell and Polcyn (2005); to Plioplatecarpidae by Tokaryk (1993), Bardet et al. (2005) and Cuthbertson et al. (2007); to Plioplatecarpini by Russell (1967), Fernández et al. (2008) and Komishi and Caldwell (2009); to Plioplatecarpinae by Holmes (1996), Martin and Crame (2006), Cuthbertson and Holmes (2015) and Driscoll et al. (2019); and to Plioplatecarpini by Longrich et al. (2024).