Ken'ichi can be written using different kanji characters and can mean:

• 賢一, "wise, one"
• 健一, "healthy, one"
• 憲一, "constitution, one"
• 謙一, "humble, one"
• 建一, "build, one"
• 研一, "polish, one"
• 兼一, "concurrently, one"

The name can also be written in hiragana or katakana.

• Kenichi Abe (阿部 健市, born 1923, death date unknown), Japanese World War II flying ace
• Ken'ichi Chen (建一, born 1956), Japanese chef and restaurateur
• Kenichi Ego (賢一, born 1979), Japanese football player
• Kenichi Endō (憲一, born 1961), Japanese actor
• Kenichi Enomoto (健一, 1904–1970), Japanese singing comedian
• Kenichi Fukui (謙一, 1918–1998), Japanese chemist
• Kenichi Furuya (古屋 健一, 1912–1988), Japanese ice hockey player
• Ken'ichi Kasai (ケンイチ, born 1970), Japanese anime director
• Keni'chi Kōbō (賢一, born 1973), former sumo wrestler
• Kenichi Konishi (健一, born 1909), Japanese field hockey player
• Kenichi Hagiwara (健一, born 1950), Japanese actor and lead singer
• Kenichi Horie (謙一, born 1938), Japanese solo yachtsman
• Kenichi Kaga (健一, born 1983), Japanese footballer for Júbilo Iwata
• Ken-ichi Kimura (architect) (木村 建一, born 1933), Japanese architect
• Kenichi Kimura (rugby union) (木村 賢一, born 1968), Japanese rugby union player
• Kenichi Konishi (小西 健一, born 1909), Japanese field hockey player
• Kenichi Kuboya (健一, born 1972), Japanese golfer
• Kenichi Matsuyama (ケンイチ, born 1985), Japanese actor
• Kenichi Mikawa (憲一, born 1946), Japanese singer
• Ken'ichi Mishima (三島 健一, born 1942), Japanese philosopher
• Kenichi Mizuno (賢一, born 1966), Japanese politician
• Kenichi Momoyama (虔一, 1909–1990), first son of Prince Ui of Korea by Lady Jeong
• Kenichi Mori (賢一, born 1984), Japanese footballer for Mito HollyHock
• Luke Kenichi Muto (謙一), Japanese Anglican bishop
• Kenichi Nishi (健一, born 1967), Japanese video game designer
• Kenichi Ogata (voice actor) (賢一, born 1942), Japanese voice actor
• Kenichi Ogawa (堅一, born 1988), Japanese boxer
• Kenichi Ono (健一, born 1958), Japanese voice actor and actor
• Kenichi Ohmae (研一, born 1943), Japanese business and corporate strategist
• Kenichi Okada (健一, born 1980), rhythm guitarist of Japanese band MERRY (previously CRESCENT and Syndrome)
• Kenichi Sasaki (佐々木 健一, born 1950), Japanese handball player
• Kenichi Shimokawa (健一, born 1970), Japanese football goalkeeper
• Kenichi Shinoda (建市, born 1942), Japanese yakuza boss of Yamaguchi-gumi
• Kenichi Sone (曽根 健一, c. 1909–1946), Japanese internment camp commander and war criminal
• Kenichi Sonoda (健一, born 1962), manga artist and anime character designer
• Kenichi Suzuki (disambiguation), multiple people
• Kenichi Suzumura (健一, born 1974), Japanese voice actor
• Kenichi Tago (健一, born 1989), Japanese professional badminton player
• Kenichi Takahashi (健一, born 1973), Japanese long-distance runner
• Ken-ichi Ueda (植田 憲一, born 1946), Japanese scientist
• Kenichi Uemura (健一, born 1974), Japanese football player
• Kenichi Umezawa (梅沢 賢一, born 1957), Japanese fencer
• Kenichi Yamada (山田 健一, born 1947), Japanese golfer
• Kenichi Yamakawa (健一, born 1953), Japanese author and rock musician
• Kenichi Yamamoto (yakuza) (健一, 1925–1982), founder of the Yamaken-gumi yakuza gang
• Ken'ichi Yoshida (literary scholar) (健一, 1912–1977), Japanese author and literary critic
• Kenichi Yoshida (animator) (健一, born 1969), Japanese animator and character designer
• Kenichi Yumoto (健一, born 1984), Japanese freestyle wrestler

• Kenichi (ケンイチ), the main character of the 2001 anime film Metropolis
• Kenichi Shirahama (兼一), the main character of the manga series Kenichi: The Mightiest Disciple
• Kenichi Mitsuba (三葉ケン一), a character from Ninja Hattori-kun franchise.
• Kenichi Natsuki (菜月賢一), a character from Re:Zero - Starting Life in Another World

• Chief Detective Kenichi, a manga series by Osamu Tezuka
• Kenichi Yamamoto (disambiguation)