Patients with urethral stricture due to any type of trauma, hypospadias or gender dysphoria suffer immensely from impaired capacity to urinate and are in need of a new functional urethra. Tissue engineering with decellularization of a donated organ recellularized with cells from the recipient patient has emerged as a promising alternative of advanced therapy medicinal products. The aim of this pilot study was to develop an ovine model of urethral transplantation and to produce an individualized urethra graft to show proof of function in vivo. Donated urethras from ram abattoir waste were decellularized and further recellularized with autologous buccal mucosa epithelial cells excised from the recipient ram and expanded in vitro. The individualized urethral grafts were implanted by reconstructive surgery in rams replacing 2.5 ± 0.5 cm of the native penile urethra. After surgery optimization, three ram had the tissue engineered urethra implanted for one month and two out of three showed a partially regenerated epithelium. Further adjustments of the model are needed to achieve a satisfactory proof-of-concept; however, we interpret these findings as a proof of principle and a possible path to develop a functional tissue engineered urethral graft with de- and recellularization and regeneration in vivo after transplantation.