Redondo was born May 4, 1928, in Candon, Ilocos Sur, in what was then the American territory the Philippine Islands. His brother, Francisco "Quico" Redondo, was a comics artist as well.
He studied architecture at the Mapúa Institute of Technology in Manila until fourth year, and did not finish having been lured into drawing in comics and working in advertising.
Redondo began his career drawing Filipino komiks serials, which were written by his brother Virgilio, including Mars Ravelo's Darna series. In 1969 and 1970 Redondo did a four-page serial Mga Kasaysayang Buhat sa Bibliya (Tales from the Bible) in each issue of Superyor Komiks Magasin, which was produced by his own company, Nestor Redondo Publications. This company launched a program of on-the-job training for young writers and artists.
In the 1970s, Redondo began to do work for publishers in the United States. His earliest U.S. credit is penciling and inking the ten-page story "The King Is Dead", by writer Jack Oleck, in DC Comics' House of Mystery #194 (Sept. 1971). Through the 1970s, Redondo drew dozens of such supernatural anthology stories for DC titles including House of Secrets, The Phantom Stranger, Secrets of Sinister House, The Unexpected, Weird War Tales, and The Witching Hour. He drew six of the seven issues of Rima, the Jungle Girl (May 1974 - March 1975), based on the heroine of a Victorian novel, as well as Swamp Thing #11-23 (Aug. 1974 - July 1976), and DC's tabloid-sized one-shot collection of Bible stories, cover-titled The Bible but officially titled Limited Collectors' Edition #C-36 (July 1975). Nestor Redondo and his brother Frank Redondo (b. 1942, d. 2010) often collaborated and credited together as the "Redondo Studio" most notably on the Ragman series for DC.
In 1970, Redondo was approached by Vincent Fago of Pendulum Press to illustrate stories in their new line of comic book adaptations of literary classics. Redondo offered to help Fago recruit some of his fellow Filipino comics artists, which he did; these artists ended up illustrating almost every comic Pendulum produced. From 1973–1979, Redondo illustrated many stories in the Pendulum Illustrated Classics line, including Dracula and Dr. Jekyll and Mr. Hyde adaptations reprinted by Marvel Comics three years later as Marvel Classics Comics. Other adaptations illustrated by Redondo for Pendulum included The Great Adventures of Sherlock Holmes, some Edgar Allan Poe stories, The Odyssey, and Romeo and Juliet. In addition, Redondo illustrated a Pendulum comic book history of the American Civil War, and biographies of Madame Curie, Albert Einstein, and Abraham Lincoln.
In the mid-1980s, Redondo inked the Eclipse Comics time-travel series Aztec Ace, by writer Doug Moench and pencilers Michael Hernandez and Dan Day. In 1990, he contributed to the second issue of the Marvel Comics superhero series Solarman as well as to an issue of Innovation Comics' Legends of the Stargrazers. Redondo collaborated with Roy Thomas on an adaptation of Robert E. Howard's Marchers of Valhalla in the mid-1990s, but the finished comic book never saw print.
More regularly, Redondo contributed to various Christian comics. In addition to the DC Comics' 1975 one-shot collection of Bible stories, Redondo illustrated Marx, Lenin, Mao and Christ, published in 1977 by Open Doors (and reprinted in 2010 by Calvary Comics); Pendulum's Ben-Hur, published in 1978; Born Again Comics #2 (featuring the story of Filipino actor-turned-evangelist Fred Galang) in 1988; Aida-Zee, Behold 3-D, and Christian Comics & Games #0 and #1, produced in the 1990s by The Nate Butler Studio. Redondo was a panelist for the first Christian comics panel discussion of the San Diego Comic Convention in 1992.
In preparation for the First International Christian Comics Training Conference in Tagaytay, the Philippines in January 1996, Redondo wrote On Realistic Illustration for his main teaching session, but died before he was able to deliver it personally. Redondo was living in Los Angeles County, California, at the time of his death.
In 1979, Redondo received the Inkpot Award at the San Diego Comic Convention.