On the review aggregator website Rotten Tomatoes, the first season has an approval rating of 71% with an average rating of 5.9/10 based on 28 reviews. The website's critics consensus is, "It's intermittently funny, but in most respects, BoJack Horseman pales in comparison to similar comedies." On Metacritic, the season received a score of 59 out of 100, based on 13 critics, indicating "mixed or average reviews". Erik Adams' review of the first six episodes gave the series a C+ grade; in the review, Adams wrote that the show "spoofs the emptiness of celebrity, but does so without any novelty or true insight". Willa Paskin, writing for Slate, was more enthused. "[It] is perhaps a little more clever than it is uproariously funny, but it is often very clever, and, moreover, well-tuned to the ludicrousness of the sort of low-level fame that surrounds BoJack". She likened it to 30 Rock in its ability to "[present] big ideas without having to commit to them". Chris Mitchell of Popzara was equally optimistic about the show's future, saying that "Fans of FX's Archer or Fox's Bob's Burgers will definitely want to check this one out, as its rapid-fire delivery is always consciously spot-on". The New York Times described the show as "hilarious and ribald".[49] Margaret Lyons of Vulture gave a positive review, describing it as "radically sad. I love it."
The second half of the season, however, received much more positive reviews. Ben Travers of IndieWire believed one possible reason for mixed reviews of the show was critics reviewing only the first half of the season, with the second half changing drastically in tone and developing a darker and deeper meaning. This change was so drastic that it led to IndieWire changing its policy to only review entire seasons of shows on Netflix, instead of just the first six episodes, which would have boosted BoJack Horseman's C+ grade.
Keith Uhlich of The A.V. Club named the first season of BoJack Horseman the fourth-best motion picture of 2014.
The second season received universal acclaim. On Rotten Tomatoes, the second season holds an approval rating of 100% with an average rating of 8.7/10 based on 22 critics. The website's critics consensus is, "Bojack Horseman truly comes into its own during season two, maturing into an ambitious comedy that sensitively blends wackiness with dark, nuanced drama." On Metacritic, the season has a score of 90 out of 100, based on 7 critics. Emily VanDerWerff of Vox wrote that the show had "found its footing beautifully in season two, earning the title of not just the streaming service's best show, but of one of television's best shows". Liz Shannon Miller of IndieWire gave the series a grade of "A−", praising the depth of the show's storyline, the voice cast and the superior comedy in comparison to the first season. Vikram Murthi of The A.V. Club also gave the series an "A−", commenting that "for the most part, it's an entirely unique, funny, and melancholic exploration into the heart and mind of someone struggling to put his life back on track after a series of dark turns".
Chuck Bowen of Slant Magazine awarded the series four-and-a-half stars out of five, commenting that "BoJack Horseman's second season is an even more confident blend of the various tones it experimentally donned last year, as it's simultaneously melancholic, angry, goofy, playful, and often uproariously funny in a distinctively ineffable what-the-fuck fashion". Entertainment Weekly gave the series a B rating, stating it was "one of TV's best meta-skewers of Hollywood".
The third season received near-universal acclaim. On Rotten Tomatoes, the third season has an approval rating of 100% with average rating of 9.1 based on 31 reviews. The website's critics consensus is, "Skillfully puncturing the idea of celebrity and our culture's bizarre obsession with it, BoJack Horseman's third season continues its streak as one of the funniest and most heartbreaking shows on television." On Metacritic, the season received a score of 89 out of 100, based on 12 reviews. Daniel Fienberg of The Hollywood Reporter lauded the season, commenting that the show "evolved from frothy talking-animal Hollywood satire to character-rich treatise on depression in its first season, deepened and darkened into one of TV's best shows in its second season and gallops into its third season with a profound confidence". Entertainment Weekly gave the series an A rating, stating the season is "more digressive than the show's first two years, and much more open-ended, sending core characters in different directions" and that it "builds to one of the funniest, weirdest, and most profound moments ever seen in a television show".
The A.V. Club awarded the series an A−, commenting that "Netflix has taken it upon itself to add BoJack to the line of TV's famous antiheroes" and praising the show for improving with each series. Chris Cabin of Collider gave the show four out of five stars, stating "BoJack Horseman ends up becoming a thrilling, rueful study of the psychological games and uniquely vain, notably capitalistic decision-making that powers the entertainment industry". They went on to praise the show's humor; "through its venomous jokes and unrelenting, uproarious gags, the series also recognizes how charming, joyful, and galvanizing entertainment for entertainment sake can be, no matter how stupid or silly it may seem".
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".
Keeping up with the performance of previous seasons, the fifth season received widespread acclaim. Based on 48 reviews, the season has an approval rating of 98% with average rating of 9.3/10 on Rotten Tomatoes. The website's critics consensus is, "BoJack Horseman continues confidently down the thematic rabbit hole with a fresh and poignant season that's as devastating as it is hilarious." On Metacritic, it holds a score of 92 out of 100 based on 6 reviews. Indiewire gave the season an "A" calling it another brilliant season and saying the series has become so great that it is "beyond reproach". Multiple critical reviews have praised the episode "Free Churro", calling it one of the series' best episodes and giving it Emmy buzz for both the writing and Will Arnett's monologue. Les Chappell of The A.V. Club observed that the episode "The Dog Days Are Over", in which Diane Nguyen takes an impromptu trip to Hanoi, can be seen as a commentary on the "identity crisis elements" of having the Vietnamese-American character Diane voiced by a white actress.
The sixth season has also received wide acclaim. On Rotten Tomatoes, the season holds a 96% approval rating with an average rating of 9.2/10 based on 55 reviews, with a critics' consensus that reads: "Bittersweet and brilliant to the very end, BoJack Horseman's final season manages to keep surprising viewers with its empathy and depth, solidifying its place as one of TV's greatest offerings." On Metacritic, the first part of season six holds a score of 93 out of 100 based on 6 reviews, while the second part holds a score of 91 out of 100 based on 8 reviews. Jen Chaney of Vulture called it "more clever, intelligent, and multilayered than 95 percent of comedies on television or any other platform".