Keiichi is a masculine Japanese given name. Notable people with the name include:

• Keiichi Akimoto (秋元 啓一, 1930–1979), Japanese photographer
• Keiichi Arawi (あらゐけいいち, born 1977), Japanese manga artist
• Keiichi Hayashi (林 景一, born 1951), Japanese diplomat
• Keiichi Ishizaka (石坂 敬一, 1945 – 2016), Japanese music director
• Keiichi Itakura (板倉 啓壹, born 1942), Japanese molecular biologist
• Keiichi Kawanaka (川中 恵一, born 1973), Japanese butterfly swimmer
• Keiichi Kimura (photographer) (木村 恵一, born 1935), Japanese photographer
• Keiichi Kimura (swimmer) (木村 敬一, born 1990), Japanese Paralympic swimmer
• Keiichi Nanba (難波 圭一, born 1957), Japanese voice actor
• Keiichi Kuwabara (桑原 敬一, born 1980), Japanese voice actor
• Keiichi Noda (野田 圭一, born 1943), Japanese voice actor
• Keiichi Nozaki (野崎 圭一, born 1961), Japanese music producer
• Keiichi Okabe (岡部 啓一, born 1969), Japanese music composer
• Keiichi Ozawa (小澤 啓一, born 1933), Japanese film director
• Keiichi Sanada (真田 圭一, born 1972), Japanese shogi player
• Keiichi Sigsawa (時雨沢 恵一, born 1972), Japanese light novel author
• Keiichi Sonobe (園部 啓一, born 1960), Japanese voice actor
• Keiichi Suzuki (composer) (鈴木 慶一, born 1951), Japanese music composer
• Keiichi Suzuki (speed skater) (鈴木 惠一, born 1942), Japanese speed skater
• Keiichi Tsuchiya (土屋 圭市, born 1956), also known as the Drift King, Japanese racing driver
• Keiichi Yano (矢野慶一), video game designer

Fictional characters

• Keiichi Maebara (前原 圭一), a character in the sound novel Higurashi no Naku Koro ni
• Keiichi Morisato (森里 螢一), a character in the manga series Oh My Goddess!
• Keiichi Sumi (角 圭一), a character in the manga series Junjo Romantica