Author Natsume Akatsuki wrote KonoSuba with the deliberate intention of setting a contrast against typical fantasy genre tropes, drawing inspiration from video games like Wizardry and Final Fantasy as well as tabletop role-playing games.

Akatsuki had previously submitted a draft to a light novel contest but was told he needed to work on the basics of novel writing, so he kept practicing before pursuing the series more seriously.

The character Mitsurugi was originally conceived as a rival to Kazuma's party, but ended up becoming just another eccentric and foolish character instead.

When Akatsuki first learned in January 2015 that an anime adaptation was greenlit, he was living in Fukui Prefecture and could not attend the Tokyo meeting because his house was buried in snow, so he was informed of the adaptation by phone instead.

Director Takaomi Kanasaki and series composer Makoto Uezu had previously worked together on the anime 'Is This a Zombie?', and each specifically requested the other join the KonoSuba project, which is how they ended up teaming up again.

For the lead role of Kazuma, director Kanasaki repeatedly rejected candidates because the role required difficult emotional control and heavy dialogue; voice actor Jun Fukushima was only chosen after his third audition tape.

During a test recording, Jun Fukushima improvised the line 'Hai, Kazuma desu' (Yes, I'm Kazuma) to lighten the mood on set; the joke amused voice actor Tetsu Inada (the Rough Man) so much that similar ad-libs were eventually incorporated into the finished show.

Sora Amamiya was cast as Aqua after her audition performance of the 'God Blow' line stood out to the director for its expressive range and evident enjoyment in mocking Kazuma.

Unlike typical anime recording sessions where only a sound director gives instructions, director Kanasaki personally directed the voice actors in the recording booth alongside sound director Yoshikazu Iwanami.

Because Fukushima wrote large amounts of ad-libbed dialogue into the script, the production booked one of Japan's largest recording studios so nearly the entire main cast could perform scenes together simultaneously, resulting in unusually short recording sessions.

The 'ko-no-su-ba' jingle phrases inserted between scenes were left up to the voice actors themselves to decide, with Ai Kayano typically asking who would say the line and Fukushima offering casting suggestions.

Composer Masato Koda was recommended for the score because he had previously composed music for the game Monster Hunter, and series composer Uezu knew him personally; the director asked that the music always remain 'cool' even when the show itself got silly.

Before the first season aired, KonoSuba did not even rank in the top 20 of Akiba Souken's 2016 winter anime anticipation poll, but after broadcast it became popular enough to earn a second season.

Following the success of the anime adaptation, the light novel's sales grew from 400,000 copies before the announcement in May 2015 to over 1.5 million copies by March 2016, according to publisher Kadokawa.

By November 2021, the KonoSuba light novel series had reached 10 million copies in circulation worldwide.

Chief animation director Koichi Kikuta intentionally based his character designs on children's shows like Pokémon, feeling the story's tone was similar, which led to character animation that was criticized by some as inconsistent or 'off-model' despite being a deliberate artistic choice to bring out each character's individuality.