In response to the emergence of devil facial tumour disease (DFTD) and the resultant population declines, a captive insurance population of Tasmanian devils was established in 2006 with a free-ranging subpopulation later established on Maria Island, Tasmania. We aimed to quantify the impact of introducing a top-order predator to a naïve ecosystem and more broadly provide evidence for the efficacy of assisted colonisations. Using a metabarcoding approach, DNA was amplified from six pilot samples targeting a ~100 bp region of the 12S mitochondrial gene, with and without a predator-specific blocking oligonucleotide, and sequenced on a Miseq platform. Sequences were filtered, cleaned and assigned to taxa using the OBITools program. We identified a total of 14 prey items, six marsupials, one monotreme, two fish, one marine mammal, three birds and one reptile, none of which are vulnerable species of concern. The blocking oligonucleotide reduced the amplification of Tasmanian devil DNA by 50% without affecting amplification of closely related species. These results confirm that as scavengers, devils have a diverse diet, feeding primarily on other marsupials and validates the methodology used. Understanding the impact of an introduced predator is essential to determining the success of an assisted colonisation as a conservation tool. The validated methods of the present study will enable both a more in-depth analysis of devil predation on Maria Island and help to inform future studies of a similar nature.