The debut came on January 3, 1989, and the networks weren't paying attention, which is exactly how he wanted it. NBC and CBS built their late-night for middle-aged white audiences; he built his for everyone those shows ignored. The Arsenio Hall Show was the first nationally syndicated late-night hosted by a Black man, and it ran on hip-hop and a 'Dog Pound' audience section named after the Cleveland Browns' fan base. Mariah Carey, Snoop Dogg, and Boyz II Men got early TV exposure there. Bill Clinton played saxophone on it during his 1992 campaign and likely moved poll numbers doing it.
When the show ended in May 1994, he didn't scramble to stay. Leno and Letterman had caught up in the ratings and the competition wasn't sustainable. A decade largely off the radar followed. He won Celebrity Apprentice in 2012, which was enough to get CBS interested in a revival, but The Arsenio Hall Show returned in 2013 and CBS canceled it after one season. He's back on the stand-up circuit now, taking voice acting roles, occupying a much smaller footprint than the one he built. The orbit shrank, but the guy who built it seems fine with that.
His monologue catchphrase 'things that make you go hmmm' wasn't just a joke setup. C+C Music Factory turned it into a #1 hit in 1991. He also released a rap album under the alter ego 'Chunky A,' featuring Ice-T and Paula Abdul, which is the kind of decision that only makes sense in 1989. Before any of that, he spent 1986 to 1988 as the original voice of Winston Zeddemore in The Real Ghostbusters cartoon. He and Eddie Murphy have been close friends for nearly 40 years; he's the godfather to Murphy's oldest daughter. The introduction was Murphy's mother's idea. She thought they looked alike.