Immunotherapy has been an important treatment option for bladder cancer. Since the 1970s, intravesical Bacillus Calmette-Guérin (BCG) therapy has been the standard of care for non-muscle-invasive bladder cancer. Recently, immune checkpoint inhibitors have been approved and used in the clinic for treating metastatic bladder cancer. However, immunotherapy does not work for everyone, which is shown by the high recurrence rate for patients who have undergone BCG therapy and low response rate for immune checkpoint blockade therapy. Given that immunotherapies work on modulating the tumour microenvironment (TME), there is a need to investigate how cellular and extracellular components in the bladder TME generate immunosuppressive signals that may skew therapeutic response. Here, we performed transcriptomic analysis on a public bladder cancer dataset to screen for immunosuppressive genes and estimate the immune cell composition of tumour samples. We also used a cytokine multiplex bead-based assay to profile soluble factors from the supernatant of bladder cancer cell lines as an additional screen for immunosuppressive cytokines. In combination, these findings will facilitate the selection of suitable drug targets to bolster current bladder cancer immunotherapies.