Poekilopleuron bucklandii was named by Eudes-Deslongchamps (1837). Its type specimen is Muséum du Caen (destroyed), a set of postcrania, and it is a 3D body fossil. Its type locality is La Maladrerie quarry, Caen, which is in a Bathonian marine limestone in the Calcaires de Caen Formation of France. It is the type species of Poekilopleuron. It was considered monophyletic by Allain and Chure (2002).

It was synonymized subjectively with Megalosaurus bucklandii by Mansel-Pleydell (1888), Lydekker (1888) and Paul (1988); it was synonymized subjectively with Megalosaurus dunkeri by Newton (1889); it was synonymized subjectively with Megalosaurus bucklandi by Woodward and Sherborn (1890); it was synonymized subjectively with Megalosaurus poikilopleuron by Huene (1923) and Huene (1926); it was recombined as Megalosaurus (Poekilopleuron) bucklandi by Bigot and Cardinet (1938); it was synonymized subjectively with Megalosaurus poekilopleuron by Rioult (1978); it was misspelled as Poikilopleuron bucklandi by Stromer (1915), Huene (1915), Piveteau (1923), Molnar (1980), Molnar and Pledge (1980), Buffetaut (1983), Buffetaut et al. (1991), Bakker et al. (1992), Buffetaut et al. (1993), Molnar et al. (1996), Currie and Padian (1997), Buffetaut (1997), Allain and Chure (2002), Rauhut (2003), Holtz et al. (2004), Allain (2005), Galton and Knoll (2006), Wu et al. (2009), Carrano et al. (2012), Rauhut et al. (2016), Razzolini et al. (2016), Gand et al. (2018) and Brignon (2018).