Plioplatecarpidae was named by Dollo (1884). It was considered monophyletic by Cuthbertson et al. (2007).

It was synonymized subjectively with Mosasauridae by Kuhn (1966); it was misspelled as Plioplatecarinae by Polcyn and Everhart (2008); it was reranked as the subfamily Plioplatecarpinae by Russell (1967), Thurmond (1969), Russell (1970), Welles and Gregg (1971), Thurmond and Jones (1981), Wright and Shannon (1988), Wiffen (1990), Páramo (1994), Holmes (1996), Lingham-Soliar (1996), Páramo-Fonseca (2000), Bardet et al. (2005), Polcyn and Bell (2005), Martin and Crame (2006), Cuthbertson et al. (2007), Fernández et al. (2008), Konishi et al. (2010), Konishi and Caldwell (2011), Konishi et al. (2012), Bell et al. (2013), Cuthbertson and Holmes (2015), Hornung et al. (2018), Driscoll et al. (2019), Strong et al. (2020), Kiernan and Ebersole (2023), Plasse et al. (2024) and Rivera-Sylva et al. (2024).

It was assigned to Pythonomorpha by Zittel (1890); to Mosasauria by Kuhn (1946); to Natantia by Bardet et al. (2005); to Russellosaurina by Polcyn and Bell (2005), Cuthbertson et al. (2007), Konishi et al. (2010), Konishi and Caldwell (2011), Konishi et al. (2012), Cuthbertson and Holmes (2015), Kiernan and Ebersole (2023) and Plasse et al. (2024); and to Mosasauridae by Russell (1967), Thurmond (1969), Russell (1970), Welles and Gregg (1971), Thurmond and Jones (1981), Wright and Shannon (1988), Wiffen (1990), Páramo (1994), Holmes (1996), Lingham-Soliar (1996), Páramo-Fonseca (2000), Martin and Crame (2006), Fernández et al. (2008), Polcyn and Everhart (2008), Bell et al. (2013), Hornung et al. (2018), Driscoll et al. (2019), Strong et al. (2020) and Rivera-Sylva et al. (2024).