Yoshii (written: 吉井) is a Japanese surname. Notable people with the surname include:
Hidekatsu Yoshii (吉井 英勝, born 1942), Japanese politicianYoshii Isamu (吉井 勇, 1886–1960), Japanese poet and playwrightKanae Yoshii (吉井 香奈恵, born 1993), Japanese idol, singer and actressKosuke Yoshii (吉井 孝輔, born 1986), Japanese footballerManami Yoshii (吉井 愛美, born 1981), Japanese AV actressMasato Yoshii (吉井 理人, born 1965), Japanese baseball playerNaoto Yoshii (吉井 直人, born 1987), Japanese footballerRei Yoshii (吉井 怜, born 1982), Japanese actressSayuri Yoshii (吉井 小百合, born 1984), Japanese speed skater