With the availability of a potential treatment to reverse male hypogonadism (MH), the primary aim of this case series study was to determine independent relationships between this condition and the nutritional, functional, and quality of life characteristics of advanced cancer patients (ACP). Free testosterone levels were measured in 100 male patients with advanced lung and gastrointestinal (GI) cancer. Routine blood markers of nutrition and inflammation, self-reporting questionnaires for symptom, nutrition, and functional status along with handgrip dynamometry were assessed for all patients at bedside. Almost half of this cohort underwent further assessments (body composition, lower body strength, in depth quality of life and fatigue questionnaires) at the McGill Nutrition and Performance Laboratory (mnupal.mcgill.ca). Multiple regression analyses were performed to identify independent correlations between free testosterone and the above measures. Seventy-six percent of patients were diagnosed with MH. Using multiple linear regression, low free testosterone (31.2 pmol/L) was independently associated with lower albumin (B = –3.8 g/L; 95% confidence interval CI –6.8:–0.8), muscle strength (–11.7 lbs; –20.4: –3.0) and mass in upper limbs (–0.8 kg; –1.4: –0.1), overall performance status (Eastern Cooperative Oncology Group Performance Scale, ECOG PS 0.6; 0.1:1.1), cancer-related fatigue (Brief Fatigue Inventory, BFI 16.7; 2.0: 31.3), and overall quality of life (MQoL total score –1.42; –2.5: –0.3). Thus MH seems to be highly prevalent in ACP, and it is independently associated with important nutritional, functional, and quality of life characteristics in this patient population.