A persistent challenge to effective eradication of tumours by the immune cells is the immunosuppressive tumour microenvironment (TME) that develops in hypoxic solid tumours. One such factor, adenosine, is a potent immunosuppressive metabolite produced by an ecto-enzymes CD73 and CD39 on tumour cells, stroma and fibroblasts, which mediates suppression of immune cells including T cells and NK cells through the A2AR, one of four adenosine receptors that include A1R, A2AR, A2BR, and A3R. Our understanding of the mechanism of action of this interaction is limited due to a lack of robust flow cytometry antibodies to A2AR. To address this problem, we have developed a novel transgenic A2AR-eGFP reporter mouse, allowing for the investigation of A2AR expression on a range of immune subsets within tumours and draining lymph nodes (dLNs), and how this expression is affected by immunotherapy. This has revealed that A2AR is highly expressed in the TME relative to the dLN, with the majority of expression on innate-like cells such as NKs and γδ T cells. Given ongoing clinical trials assessing the combination of A2AR antagonists and approved immune checkpoint inhibitors we investigated the expression of A2AR following treatment with anti-PDL-1 and/or anti-CTLA-4. Treatment results in decrease A2AR expression on tumour-infiltrating CD8+ T cells, particularly on tumour antigen-specific CD8+ T cells. Moreover, treatment with anti-PD-L1 gave rise to a novel subset of PD-1+A2AR- cells not present in non-treated mice. In summary, this reporter mouse offers exciting opportunities to investigate aspects of A2AR biology, which are important to consider when combining immunotherapy with A2AR or CD73-targeting agents for the treatment of solid cancers.