"Beast King GoLion" is a science fiction mecha anime set in a distant future where Earth has been conquered by the Galra Empire, a ruthless alien race. The story begins with five young pilots from different nations—Akira Kogane, Isamu Kurogane, Takashi Shirogane, Tsuyoshi Seidou, and Hiroshi Suzuishi—who are captured by the Galra while attempting to escape Earth. Imprisoned on the planet Galra, they endure harsh conditions and witness the empire's tyranny firsthand. After a daring escape, the group crash-lands on the planet Altea, where they encounter Princess Fala and her advisor, Raible. Altea, once a thriving civilization, has been devastated by the Galra, and its people are enslaved.

The pilots learn of the legendary robot GoLion, a powerful mecha formed by combining five lion-shaped vehicles, each piloted by one of the group. GoLion is the only weapon capable of standing against the Galra Empire. The five pilots, now united as the Voltron Force, take up the mantle of defending Altea and liberating oppressed worlds from Galra rule. Their journey is marked by battles against the empire's forces, led by the cunning Prince Sincline and his generals, as well as internal struggles and personal growth among the team members.

The narrative explores themes of resistance, unity, and sacrifice as the Voltron Force fights to restore freedom to the galaxy. The pilots' individual backgrounds and personalities—ranging from Akira's leadership and determination to Tsuyoshi's hotheadedness and Hiroshi's calm demeanor—add depth to their interactions and decision-making. The series balances episodic battles with overarching plotlines, including the mystery of Altea's past and the true nature of GoLion. As the story progresses, the team faces increasingly formidable enemies, culminating in a climactic confrontation with the Galra Emperor and the ultimate fate of the galaxy hanging in the balance.