Hernandez grew up with his four brothers and one sister, in Oxnard, California. His family embraced comics, and comics were not considered a lesser, mediocre art form. Their mother read comics and old issues were kept in large quantities in the house, to be read and re-read by all over the years. The brothers read all types of comics and enjoyed those that gave a fairly realistic depiction of family life, such as Dennis the Menace, as well as the standard super hero adventures.

Hernandez was particularly influenced by Hank Ketcham's Dennis and Dan DeCarlo's Archie comics; the children in his otherwise rather realistic stories are often drawn to resemble Ketcham's, and Jaime's character's often strike very DeCarlo-esque poses. The work of Alex Toth, Steve Ditko and Jack Kirby were also hugely influential, as well as the distinctive styles of Charles Schulz and Milton Caniff.

Hernandez has a lifelong fascination with pro wrestling, especially women's wrestling, and it has been a regular part of his work. Hernandez has also been a lifelong punk rock fan. In addition to playing in bands himself it has been a constant element of his work. Maggie and her friends are almost all punk fans, and Jaime has done a series of stories about Hopey's career as bass player for a luckless punk band.

Jaime's main contribution to Love and Rockets is the ongoing serial narrative Locas which follows the tangled lives of a group of primarily Latina characters, from their teenage years in the early days of the California punk scene to the present day. The two central characters of Jaime's cast are Margarita Luisa "Maggie" Chascarrillo and Esperanza Leticia "Hopey" Glass, whose on-again, off-again, open romance is a focus for many Locas storylines. Early on, the stories switched back and forth between Maggie's sci-fi adventures journeying around the world and working as a "prosolar" mechanic repairing rocketships, and much more realistic stories of Maggie and her friends in a grungy, mostly Latin California neighborhood known as "Hoppers". Eventually Hernandez dropped almost all of the sci-fi elements, although he does still occasionally include references to the earlier stories and he still does very occasional short stories about superheroines, robots and other sci-fi genre elements.

The Hernandez brothers announced they were ending Love and Rockets with issue 50, and that they would be doing solo books from then on. For the next few years, both brothers released many solo books, with Jaime doing several books featuring his Locas characters (including Whoa Nellie, Penny Century, and Maggie and Hopey Color Fun) and Maggie generally occupying a supporting role. Eventually they resumed doing Love and Rockets and Maggie again took center stage, but instead of the large, magazine-style format of the original issues, the book is now released in a more traditional comic book format.

The entire Locas storyline to date was collected into one 700 page graphic novel in 2004.

Hernandez has been praised for the physical beauty of his female characters as well as their complex personalities, and for years he struggled to create comparably nuanced male characters. He succeeded with the introduction of Ray Dominguez, a failed artist who was briefly Maggie's boyfriend and went on to star in many of his own stories. Hernandez has often said that Maggie and Ray both represent different aspects of his own personality.

In an interview with The Comics Journal, Hernandez admitted he'd had difficulty aging his characters, because while he'd known girls like Maggie and Hopey when he was young, he'd never known them long enough to find out what they did in adulthood. For many years time passed very slowly in Locas, but it did pass: Maggie debuted as a slight yet curvy young adult mechanic, and as Jaime developed her character she started to gain weight slowly over each comic issue because of depression and other factors. This was controversial with some fans, but Hernandez was adamant that he'd made the right decision. As he told The Comics Journal, "(Maggie) was born to be fat." Each issue made her less of a character made from lines on paper to a human being with complex layers. A few years ago Hernandez jumped the characters years ahead, aging most of them visibly and shaking up their previously established relationships. The present Maggie is now the 40-ish manager of an apartment complex with bleached blonde hair and a penchant for wearing sexy bathing suits despite her rubenesque figure. While she still strongly resembles the zaftig Maggie readers have grown used to, from some angles she now sports a double chin or bags beneath her eyes. Her relationship with Hopey is now somewhat strained, as she feels some tension over their endlessly non-committed state, and she is also somewhat frustrated with her career (or lack of one). Hopey, meanwhile, has been working with children, something unimaginable for the violent, sarcastic punk we first met.

Other work

In addition to his Locas stories, Henandez has also done occasional work for DC Comics and The New Yorker, and he has done many album covers for such artists as Michelle Shocked (earlier in his career Hernandez also did album covers for some "Nardcore" punk bands, such as Ill Repute and Dr. Know, the latter of whom featured his younger brother Ismael on bass). In September 2006, Hernandez also created the artwork for the critically acclaimed Los Lobos album The Town and the City. In the '80s Gilbert, Mario and Jaime collaborated on Mister X, a sci-fi comic book series from Vortex Press, with Jaime handling the art and Gilbert and Mario plotting. The book's noirish look has been cited as an influence by the creators of The Animated Series among other retro-futuristic works. The Hernandez brothers themselves hold little affection for it, however, with Gilbert once describing it being "like a bad zit... it just sort of happened." After the Hernandez brothers left the book on bad terms with the publisher, various other artists continued it, including Seth.

In 2006, Publishers Weekly ranked Hernandez work Ghost of Hoppers second on its critics' poll of the best comic books of 2006.

Jaime's Love and Rockets stories have been widely praised by both comic and literary critics, and many comics creators have cited him as one of the greats. As Alan Moore has put it,

An early-80s review in Publishers Weekly stated: