Seeking revenge for the murder of his close friend and mentor, Goro Numata, the headstrong and eccentric Shigeru Jo deliberately infiltrates the evil organization Black Satan. He volunteers for their cyborg enhancement program, feigning loyalty to acquire the power he needs. After undergoing surgery that transforms him into an electrically powered super-soldier, Shigeru reveals his true intentions, escapes before he can be brainwashed, and declares himself Kamen Rider Stronger.

During his escape, Shigeru encounters Yuriko Misaki, another young cyborg created by Black Satan who can transform into the Electro-Wave Human Tackle. Rescuing her, he convinces Yuriko to join his cause, and together they fight against the organization's campaign of world domination. They are soon joined by Tobei Tachibana, a veteran ally of previous Kamen Riders who acts as a mentor to the pair.

The early narrative pits Stronger and Tackle against Black Satan's high-ranking commanders, the suave and ruthless Mr. Titan and the knight-like General Shadow. These two commanders are bitter rivals, and their constant bickering over who will destroy Stronger often provides the heroes with a chance to escape. After Mr. Titan is defeated and later resurrected as the more powerful Hundred-Eyed Titan, Stronger ultimately succeeds in toppling Black Satan for good.

In the wake of Black Satan's destruction, General Shadow forms a new and more formidable terrorist network, the Delza Army. The battle against this new enemy takes a devastating turn when Yuriko, poisoned during a fight with the Delza general Doctor Kate, sacrifices her own life using a final, suicidal attack to save Shigeru. Her death profoundly affects Stronger, driving him to undergo a dangerous secondary operation that grants him a temporary but immensely powerful upgrade known as the Charge-Up form. This new power is a double-edged sword, as he must defeat his enemy within one minute or risk exploding from the excess energy.

In the final narrative arc, the six previous Kamen Riders—Rider 1, Rider 2, V3, Riderman, X, and Amazon—return to Japan to aid Stronger. Together, the seven legendary warriors unite to wage a final battle against the Delza Army, defeating General Shadow and its true leader, the Great Leader who is the original mastermind behind Shocker. The series concludes with Shigeru, having avenged his friend and honored Tackle's sacrifice, continuing his fight for justice.