Adrenocortical carcinoma (ACC) is a rare malignancy with a poor prognosis. Treatment options for ACC are limited, with resection the main intervention. Most cases present in late metastatic cases, and data regarding effective therapies is limited. We report a case of ACC in a 40-year-old woman with history of ACC postadrenalectomy, who presented with recurrent metastatic ACC in the left perinephric space. She was started on pembrolizumab which was added to her mitotane maintenance therapy. Complete radiological response was achieved after 4 cycles of pembrolizumab. As far as we know, this is the first case to achieve complete radiological response with mitotane and pembrolizumab in recurrent metastatic ACC, with negative prognostic markers and no prior radiotherapy. As our findings are in the setting of one clinical case, we suggest the need to perform a trial to assess the benefit of combining mitotane and pembrolizumab in treating metastatic ACC.