Background/Objectives: Dental rehabilitation after extended tumour resection and jaw reconstruction is challenging. The present study aimed to report the prosthetic outcome and quality of life (QoL) in patients with head and neck cancer (HNC) after microvascular alveolar ridge reconstruction. Methods: The prosthetic outcomes of all consecutive patients with HNC who underwent microvascular alveolar ridge reconstruction at the University Hospital Salzburg between 2011 and 2018 were investigated. Oral health-related QoL (OHrQoL) and overall QoL were assessed using the validated Oral Health Impact Profile-49 (OHIP-49) and Short Form-36 questionnaires. Results: During the study period, 115 consecutive patients with head and neck cancer underwent microvascular jaw reconstruction. Among them, 23.3% and 27.4% received conventional tissue-borne prostheses and implant-supported prostheses, respectively, while 48.7% did not undergo dental rehabilitation. The prosthetic outcome was not associated with tumour stage (p = 0.32). Oral health-related quality of life (OHrQoL) was best in patients with implant-supported dental rehabilitation (OHIP-49 median score = 7) and worst in those with conventional removable dentures (OHIP-49 median score = 54). The corresponding OHIP-49 median score for patients who could not undergo dental rehabilitation was 30.5. All Short Form-36 subscale scores were equal to or higher than the malignancy norm scores. Conclusions: After microvascular jaw reconstruction, approximately one-third of the HNC patients received adequate implant-supported dental rehabilitation. However, the risk of dental rehabilitation failure was 50%. The different prosthetic outcomes affected OHrQoL, but not overall QoL.