Mackie first gained attention as a writer in 1990, when he and artist Javier Saltares launched a new Ghost Rider series for Marvel, revamping the character. He stayed on as that comic book's writer until #69 in 1996. Throughout Mackie's run of over five years, the Ghost Rider's ultimate origins and nature were never explained. A later writer, Ivan Velez Jr., provided the character with a backstory shortly before the series was cancelled.
Shortly after "Ghost Rider" was cancelled, Mackie had Ghost Rider guest star in "Peter Parker: Spider-Man" and denounce Velez's origin story as being "lies" or at least incomplete. Since then, the true status of Ghost Rider/Noble Kale's origin and Dan Ketch's fate has yet to be determined.
Howard Mackie was also the author of the cult classic Ghost Rider/Wolverine/Punisher team-up mini-series "Hearts Of Darkness" (1991), and it's follow up or sequel one-shot entitled "The Dark Design" (1994). Both feature Ghost Rider's archenemy Blackheart as the primary villain. Focusing on those who walk the line between good and evil, Blackheart tries to corrupt Ghost Rider, Punisher, and Wolverine by promising them their fondest desires in an attempt to persuade the trio to assist Blackheart in destroying Mephisto. Blackheart ultimately fails in his attempt, and the group eventually follows Blackheart back into his own realm for a final confrontation.
In 1992 he became a regular writer of Web of Spider-Man with #85. He would remain on various Spider-Man titles through the Clone Saga and beyond, finally leaving 9 years later with The Amazing Spider-Man Vol.2 #29 in April, 2001. Mackie's tenure on the Spider-Man books coincided with some of the most controversial stories in the character's history. Interviews with both Mackie and other creators and editors from the time indiciate that there was a lot of collective decision making and editorial interference during that period.
Mackie also worked for the X-Men line, writing the spin-off title X-Factor from #115-149 (1995-1999) as well as its successor Mutant X title (1999). He also wrote several miniseries featuring Gambit, Wolverine, and Rogue.