Originally, a project called "God Mazinger" was planned to directly continue the world of Great Mazinger, but it was shelved due to poor merchandise sales for Great Mazinger.

To capitalize on the UFO boom in Japan at the time, the film 'Uchū Enban Dai Sensō' (1975) was essentially used as a pilot film and adapted to fit the Mazinger universe, which resulted in the TV series Grendizer – the series thus has remake characteristics of this film.

Grendizer was Toei's first major robot anime production to establish extraterrestrials as central antagonists; this concept of 'invasion from space' subsequently became the standard for subsequent robot anime such as Daikuu Maryuu Gaiking and Chōdenji Robo Combattler V.

The return of Kōji Kabuto from Mazinger Z was not an original idea of the creators, but an explicit demand from the television network Fuji TV (through Kōji Bessho), as the character was very popular with audiences; the production team was initially divided on this and had to convince the screenwriters first.

When it became known that Kōji Kabuto was to appear in the new series, some of his fans were so upset that they sent razor blades to producer Toshio Katsuta.

Former producer of Mazinger Z and Great Mazinger, Kenji Yokoyama, later admitted that he didn't like it at all when he learned that Kōji Kabuto would continue to appear in Grendizer, as he felt that the character he himself had cultivated was being taken from him.

Episode 25 featuring the character Naida Baron was based on a manga episode by Gō Sakurada; director Tomoharu Katsumata was so impressed by it that, with Sakurada's permission, he created an anime adaptation of this story.

Originally, the character Banta Arano was supposed to be the pilot of the Drillspacer, but because the team composition was too similar to that of Getter Robo, the character Maria was introduced as the pilot instead at short notice – a decision that proved popular with audiences and improved viewership ratings.

All the music of the series – opening songs, insert songs and background music – was composed and arranged by Kikuchi Shunsuke; for the music, the series received the JASRAC Prize in the "Foreign Use" category and later the international JASRAC Prize.

Despite the long run of 74 episodes, the series achieved an average viewership rating of 20.9%, with a peak of 27.6% at episode 21.

The female protagonist Hikaru Makiba was the least popular heroine among female viewers throughout the entire Mazinger series; even her voice actress Chiyoko Kawashima stated that Hikaru would have been more popular if she hadn't piloted mechs.