The fourth season also received wide acclaim. On Rotten Tomatoes, the season holds a 97% approval rating with an average rating of 8.7/10 based on 35 reviews. The website's critics consensus is, "BoJack Horseman's fourth season finds the show continuing to fearlessly traverse the emotional gamut - with results that are heartbreaking as often as they are hilarious." Metacritic awarded the show a score of 87 out of 100 based on 5 reviews. Liz Shannon Miller of IndieWire gave the series an "A" grade, commenting that "by the end of the season, we know these characters, and this show, far better than ever before. BoJack's signature tropes—the background visual jokes, the animal puns, the brutal moments of sadness—remain reliably consistent, but turns the focus largely inward, ensuring that some of the more outlandish plots support and highlight the more emotional storylines".
Bethonie Butler of The Washington Post lauded the series, praising the installment as "moving and unexpected" and that "it offers hope but never ignores the sorrows that are inevitable in real life". Mike Hale of The New York Times also gave a positive review, commenting that the "material has the snap and the poignancy we've grown accustomed to" and that "while nothing matches the adventurousness of season three's underwater film festival episode, season four's ninth episode—narrated from the future by a distant descendant of Princess Carolyn's—is a devastating example of what BoJack can do at its best".
There aren't any new, notable characters for the season.