Background and Objectives: Human umbilical cord blood serum (HUCBS) stands out as a potent adjunct to conventional therapies for ocular surface disorders (OSDs) caused by, among many, autoimmune systemic syndromes. By expediting ocular surface regeneration and fostering epithelial integrity, HUCBS not only enhances subjective patient experiences but also improves objective clinical indicators. This makes it particularly useful in patients with corneal ulcers through ocular surface regeneration and anti-inflammatory activity. This study aims to explore the efficacy of HUCBS in patients who had previously received other treatments unsuccessfully. Materials and Methods: This study was a prospective, non-comparative, interventional case series study involving 49 patients (30 females and 19 males) aged 15–82 years with severe OSDs who were unresponsive to standard treatments. The study was conducted at the San Marco Hospital, Catania, Italy. Patients were categorized into four groups based on the etiology of their severe OSDs: Group I consisted of twenty four patients with filamentary keratitis and corneal ulcers associated with rheumatologic diseases such as Sjogren’s syndrome and systemic sclerosis; Group II comprised thirteen patients with graft-versus-host disease; Group III consisted of nine patients with corneal neurotrophic ulcers; and Group IV included three patients with Steven–Johnson syndrome. The outcomes were evaluated before and after treatment using the following assessments: OSDI (Ocular Surface Disease Index) and SANDE (Symptom Assessment in Dry Eye) questionnaires, VAS (Visual Analog Scale), Slit Lamp Examination, Esthesiometry, Lissamine Green Staining, NIBUT (Non-Invasive Break-Up Time), BUT (Break-Up Time), Fluorescein Staining with Photography and Oxford Classification, The Schirmer Test, Best-Corrected Visual Acuity (BCVA), and Meibography. Results: We observed a significant improvement in the outcomes from the SANDE, VAS, and OSDI questionnaires, The Schirmer Test, BUT, BCVA, and Oxford Classification, after treatment with UCBS. Clinical variables, such as corneal inflammation, conjunctivalization, corneal neovascularization, and pain, were also considered individually. Nevertheless, pain and inflammation reduced markedly over time until complete healing was achieved in all cases. Conclusions: Our pilot study highlights the substantial efficacy of HUCBS in patients with systemic autoimmune diseases who have shown inadequate responses to prior treatments for dry eye. This underscores the need for further comprehensive investigations in this field.