Mucocutaneous melanoma, including vulvar melanoma, is rare and has a worse prognosis and higher recurrence rate than traditional cutaneous melanoma. Diffuse cutaneous melanosis is another rare clinical presentation of metastatic melanoma. It is essential for dermatologists to be alerted to rare presentations of melanoma, to facilitate early detection. We present the first case to our knowledge of metastatic vulvar melanoma with diffuse cutaneous melanosis in a pregnant young woman. Despite the occurrence of placental metastasis, a healthy, unaffected baby was born. This case exemplifies the aggressiveness of vulvar melanoma. The genitalia should be included in routine total body skin examinations. Pregnant women with generalized melanosis may be at increased risk for placental metastasis of melanoma. Pregnancy does not alter the incidence or prognosis of melanoma; however, patients with a poor prognosis or high recurrence risk should be informed of potential pregnancy complications associated with melanoma recurrence or metastasis.