A giant cell tumor of the tendon sheath (GCTTS) is a rare benign tumor that typically presents as a solitary mass in the hand or wrist. Multifocal presentation of GCTTS is extremely rare and has been reported in only a few cases. Although the origin of multifocal giant cell tumors of the tendon sheath remains incompletely elucidated, it is a rare disorder that distinguishes itself from the diffuse form of GCTTS that typically occurs near major joints. In this case study, we report a patient with a localized multifocal GCTTS affecting the tendon sheath of the flexor pollicis longus (FPL) on the volar surface of the right thumb. The diagnosis was confirmed by both radiological and histological examinations. Additionally, the patient underwent surgical excision of the tumor masses and did not encounter any recurrence during the six-month follow-up period.